diff --git a/Documentation/Administration/Installation/Index.rst b/Documentation/Administration/Installation/Index.rst
index a944d0465b..1165675ade 100644
--- a/Documentation/Administration/Installation/Index.rst
+++ b/Documentation/Administration/Installation/Index.rst
@@ -58,3 +58,4 @@ Installation
TuneTYPO3
DeployTYPO3
LegacyInstallation
+ LegacyExtensionInstallation
diff --git a/Documentation/Administration/Installation/LegacyExtensionInstallation.rst b/Documentation/Administration/Installation/LegacyExtensionInstallation.rst
new file mode 100644
index 0000000000..4d9872ceaf
--- /dev/null
+++ b/Documentation/Administration/Installation/LegacyExtensionInstallation.rst
@@ -0,0 +1,145 @@
+.. include:: /Includes.rst.txt
+
+.. _extensions-legacy-management:
+
+====================================
+Installing Extensions - Legacy Guide
+====================================
+
+.. _extension-manager:
+.. _extension-package-manager:
+.. _extension-install:
+
+Installing an Extension using the Extension Manager
+===================================================
+
+In the backend:
+
+.. rst-class:: bignums
+
+1. Go to :guilabel:`Admin Tools > Extensions`
+2. In the Docheader, select :guilabel:`Get Extensions`
+3. Click :guilabel:`Update now`
+
+ The button is on the top right.
+
+4. Enter the name of the extension in the search field
+5. Click on :guilabel:`Go`
+6. Click on the Action icon on the left for the extension:
+
+ :guilabel:`Import and Install`
+
+ Now the extension is installed, but not activated. To activate:
+
+7. Choose :guilabel:`Installed Extensions` in the Docheader
+8. Click on the icon with a :guilabel:`+` sign for your extension
+ in the :guilabel:`A/D` column.
+
+.. _uninstall-extension-without-composer:
+
+Uninstall an Extension Without Composer
+=======================================
+
+If you installed TYPO3 via composer you should uninstall Extensions via composer.
+
+.. _uninstall-extension-without-composer-dependencies:
+
+Check Dependencies
+------------------
+
+First find out, which other extensions and functions of your TYPO3 installation
+are dependent on the extension you want to uninstall. You can find out about
+the dependencies by checking the
+`TYPO3 Extension Repository (TER) `__. Look for
+the extension you want to uninstall and the others you have installed. Read
+in each extensions manual the sections 'Dependencies' and 'Reverse dependencies'.
+
+Check whether any referrals have been made to the extension in any setup, config
+or other TypoScript files. Check if you included a plugin from the extension
+in your web site. Think of the results of removing them and finally do it.
+
+If you are working locally or on a test server you might as well try to
+uninstall the extension. The Extension Manager warns you about dependencies that
+are written in an extensions :file:`ext_emconf.php` constraints section.
+Note however that you depend on the extensions developers faithfully noting
+all dependencies in this config file.
+
+If you get an exception and cannot access the Extension Manager anymore because
+of it, you can uninstall / install extensions manually with
+:file:`PackageStates.php` as a last resort, see
+:ref:`uninstall-extension-manually`
+
+.. tip::
+ Be sure not to uninstall extensions by trial and error on production
+ systems, especially not under time pressure.
+
+.. _uninstall-extension-backend:
+
+Uninstall / Deactivate Extension via TYPO3 Backend
+--------------------------------------------------
+
+.. include:: /Images/AutomaticScreenshots/ExtensionManager/UninstallExtension.rst.txt
+
+
+Log into the TYPO3 Backend and open the module
+:guilabel:`Admin tools > Extensions`. From the menu choose
+:guilabel:`Install extensions`. You get an overview about installed extensions.
+
+On the left side you see an icon, which shows the status of each extension,
+and what you can do:
+
+* Extension Install Icon with plus sign: The extension is
+ not installed. (Click once to install)
+* Extension Uninstall Icon with minus sign: The extension is installed
+ and running. (Click once to uninstall)
+
+Next to the extension you want to uninstall click on Extension UnInstall Icon.
+After some seconds the icon changes to the grey Extension Install Icon.
+
+.. _remove-extension-backend:
+
+Remove an Extension via the TYPO3 Backend
+--------------------------------------------------
+
+After successfully uninstalling an extension via the Extension Manager you
+can permanently remove the extension by clicking on the waste-basket symbol
+"Remove" beside the extensions entry in the Extension Manager.
+
+.. _uninstall-extension-manually:
+
+Uninstalling an Extension Manually
+----------------------------------
+
+At times an extension causes a problem and the TYPO3 Backend can not
+be opened anymore due to it. In such a case the extension can be uninstalled
+manually. This is not common practise but a last resort.
+
+This can be done by removing the extensions configuration from the file
+:file:`PackageStates.php`
+
+.. rst-class:: bignums
+
+#. Open the file :file:`typo3conf/PackageStates.php`
+#. Search for your ext_key in the array.
+
+ .. code-block:: php
+ :caption: typo3conf/PackageStates.php
+
+ 'ext_key' => [
+ 'packagePath' => 'typo3conf/ext/ext_key/',
+ ],
+ //...
+
+#. Remove the entry.
+
+.. _remove-extension-manually:
+
+Removing an extension manually
+------------------------------
+
+Removing an extension manually is not common practice and should only be done
+as a last resort. You should only remove an extension that you uninstalled
+successfully. Make a backup first. Then you can permanently remove an extension
+by removing its folder at :file:`typo3conf/ext/[extensionname]`. The
+corresponding database tables can be removed in the
+:guilabel:`Admin Tools > Maintenance > Analyze Database Structure`.
diff --git a/Documentation/ExtensionArchitecture/HowTo/ExtensionManagement.rst b/Documentation/ExtensionArchitecture/HowTo/ExtensionManagement.rst
deleted file mode 100644
index 04fe4001c6..0000000000
--- a/Documentation/ExtensionArchitecture/HowTo/ExtensionManagement.rst
+++ /dev/null
@@ -1,110 +0,0 @@
-.. include:: /Includes.rst.txt
-.. index:: Extension Manager
-.. _extension-manager:
-
-====================
-Extension management
-====================
-
-.. todo: Mention Composer here
-
-Extensions are managed from the Extension Manager inside TYPO3 by
-"admin" users. The module is located at :guilabel:`Admin Tools > Extensions`
-and offers a menu with options to see loaded extensions (those that
-are installed or activated), available extensions on the server and
-the possibility to import extensions from online resources, typically
-the TER (TYPO3 Extension Repository) located at typo3.org.
-
-.. include:: /Images/AutomaticScreenshots/AdminTools/ExtensionManager.rst.txt
-
-The interface is really easy to use. You just click the +/- icon to
-the left of an extension in order to install it and follow the
-instructions.
-
-
-.. index:: Extensions; Installation
-.. _extension-package-manager:
-.. _extension-install:
-
-Installing extensions
-^^^^^^^^^^^^^^^^^^^^^
-
-There are only two (possibly three) steps involved in using extensions with TYPO3:
-
-#. You must *import* it.
-
- This simply means to copy the extensions files into the correct directory into.
- More commonly you import an extension directly from the online TYPO3 Extension Repository (TER)
- using the Extension Manager. When an extension is found located in one of the extension locations,
- it is *available* to the system.
-
- The Extension Manager (EM) should take care of this process, including updates to
- newer versions if needed.
-
- Another convenient way to install extensions is offered by using Composer (https://getcomposer.org/)
- along with the TYPO3 Composer Repository (https://composer.typo3.org/). The TYPO3 Composer Repository
- includes all TYPO3 extensions that are uploaded to TER.
-
-#. You must *load* it.
-
- In :ref:`legacy installations not based on Composer `
- an extension is loaded only if it is listed in the
- :file:`PackageStates.php` file. Extensions are loaded in the order they appear in this list.
- In :ref:`Composer installations `, all extensions in the
- :file:`composer.json` are considered as active.
-
- An enabled extension is always global to the TYPO3 Installation - you cannot disable
- an extension from being loaded in a particular branch of the page tree. The EM takes
- care of enabling extensions. It's highly recommended that the EM is doing
- this, because the EM will make sure the priorities, dependencies and
- conflicts are managed according to the extension characteristics,
- including clearing of the cache-files if any.
-
-#. You *might* be able to configure it.
-
- Certain extensions may allow you to configure some settings.
- :guilabel:`Admin Tools > Settings > Extension configuration`
- provides an interface to configure extensions that provide configuration settings. Any
- settings - if present - configured for an extension are available as
- an array in the variable :php:`$GLOBALS['TYPO3_CONF_VARS']['EXTENSIONS'][extensionKey]` and
- thus reside in :file:`config/system/settings.php`.
-
-Loaded extensions can be fetched with :php:`TYPO3\CMS\Core\Package\PackageManager::getActivePackages()`,
-available in both frontend and backend of TYPO3.
-
-This will return an array of :php:`TYPO3\CMS\Core\Package\Package` objects,
-containing the data structure for each extension. These include the properties:
-
-.. t3-field-list-table::
- :header-rows: 1
-
- - :Key,20: Key
- :Description,60: Description
-
- - :Key:
- packageKey
- :Description:
- The package key (or extension key).
-
- - :Key:
- packagePath
- :Description:
- Path to the package. Can be used to determine, if the extension is in the
- local :file:`typo3conf/ext` or system :file:`typo3/sysext` scope.
-
- - :Key:
- composerManifest
- :Description:
- A large array containing the Composer manifest. (the
- :file:`composer.json` of the extension, if it exists)
-
- - :Key:
- packageMetaData
- :Description:
- Properties of the :file:`ext_emconf.php` configuration of the
- extension, like its constraints (depends, suggests, conflicts),
- version, title, description, …,
-
-
-The order of the registered extensions in this array corresponds to
-the order they were listed in :file:`PackageStates.php` in legacy installations.
diff --git a/Documentation/Images/AutomaticScreenshots/ExtensionManager/UninstallExtension.png b/Documentation/Images/AutomaticScreenshots/ExtensionManager/UninstallExtension.png
new file mode 100644
index 0000000000..1201822ef5
Binary files /dev/null and b/Documentation/Images/AutomaticScreenshots/ExtensionManager/UninstallExtension.png differ
diff --git a/Documentation/Images/AutomaticScreenshots/ExtensionManager/UninstallExtension.rst.txt b/Documentation/Images/AutomaticScreenshots/ExtensionManager/UninstallExtension.rst.txt
new file mode 100644
index 0000000000..896b720fec
--- /dev/null
+++ b/Documentation/Images/AutomaticScreenshots/ExtensionManager/UninstallExtension.rst.txt
@@ -0,0 +1,6 @@
+.. Automatic screenshot: Remove this line if you want to manually change this file
+
+.. figure:: /Images/AutomaticScreenshots/ExtensionManager/UninstallExtension.png
+ :class: with-shadow
+
+ Select "Deactivate" in Extension Manager