Docs: Add notes on removing more than 1 license

doc/user/admin_area/license.md

@@ -107,7 +107,7 @@ For GitLab self-managed instances, you have a 14-day grace period
 before this occurs.
 
 - To resume functionality, upload a new license.
-- To fall back to Free features, delete the expired license.
+- To fall back to Free features, delete all expired licenses.
 
 ### Remove a license
 
@@ -117,6 +117,8 @@ To remove a license from a self-managed instance:
 1. On the left sidebar, select **License**.
 1. Select **Remove license**.
 
+These steps may need to be repeated to completely remove all licenses, including those applied in the past.
+
 ## License history
 
 You can upload and view more than one license, but only the latest license in the current date