ToyoGT,

Yes, sp_revokedbaccess can be used to drop users from a database.

Here is an article that gives code to identify Windows Users and SQL Users that are orphaned, and then gives the syntax for using sp_revokedbaccess to drop the unwanted users.

Removing Orphan Users from All databases on SQL Server

By Gregory A. Larsen

http://www.databasejournal.com/features/mssql/article.php/1578941

** Note that the code will work with both SQL Server 2000 and SQL Server 2005 **

Hope This Helps