[TASK] Remove chapter legacy installation from working with extensions

Author: Kiebele

Documentation/Extensions/Index.rst

@@ -22,17 +22,10 @@ Working With Extensions
         Information on how to install local extensions including site packages and custom
         extensions using Composer.
 
-    ..  card:: :ref:`Managing Extensions - Legacy Guide <extensions_legacy_management>`
-
-        This guide contains information on how to manage extensions using the
-        TYPO3 backend and the TYPO3 Extension Repository (TER) without Composer.
-        This method of managing extensions is now deprecated.
-
 
 ..  toctree::
     :hidden:
     :titlesonly:
 
     Management
     Installing Local Extensions <https://docs.typo3.org/m/typo3/tutorial-getting-started/main/en-us/Extensions/Management.html#installing-local-extensions>
-    LegacyManagement