>I use to know the trick to this but I always seem to forget it when I need it.
>
>How do I edit the referential integrity of a database.
>
>Even if I open it exlusively it tells me that I need exclusive use.
>I seem to remember something about "clean up database" but it is grayed out on my menu.

You have to make sure the database is closed first, in order to open it exclusively:

CLOSE ALL
OPEN DATABASE MyDBC EXCL

Then you can MODIFY DATABASE, right click in an empty area of the DBC, and select Edit RI...