chore: drop label of moved reference (for now)

Signed-off-by: Josh <josh.t.richards@gmail.com>

Author: joshtrichards

admin_manual/configuration_server/activity_configuration.rst

@@ -29,8 +29,7 @@ Furthermore it is recommended to configure the background job ``Webcron`` or
 ``Cron`` as described in :doc:`background_jobs_configuration`.
 
 There is also a configuration option ``activity_expire_days`` available in your
-``config.php`` (See :ref:`label-activity-app-config`) which allows
-you to clean-up older activities from the database.
+``config.php`` which allows you to clean-up older activities from the database.
 
 .. _label-activities-groupfolders:
 
@@ -87,4 +86,4 @@ exclude these users from expiration::
     'second_admin'
   ]
 
-For these users, their activity records will never deleted from the database.
+For these users, their activity records will never deleted from the database.