"Yes, there's the rub. How do you get the users out of the system and lock it down? We do not have a DBA here, so as senior programmer, I get to do most of these tasks. I haven't found a good explanation as to how to do this. Can someone enlighten me?"

I'd try it this way:

ALTER DATABASE X

SET RESTRICTED_USER

WITH ROLLBACK IMMEDIATE

This is harsh and won't make you popular, but it does kick everyone that isn't a member of db_owner role out of the system PDQ.

However, if you've got a bunch of users in the db_owner role, in addition to have other issues, you'll need to try a different approach.