3824837 - How do I prevent users from allocating to certain Company-Business Unit values?

I am managing the Company-Business Unit list under Administration > Expense > List Management. I want to prevent users from allocating charges to certain Business Unit values that are no longer in use. I have been renaming those list items to indicate they should not be used, but users are still selecting them when creating allocations.

Prevent users from selecting retired or inactive Company-Business Unit list items in expense allocations. Remove list items from List Management without affecting historical expense report data. , KBA , CON-CA-ADM , Administration , Problem