If you created overrides before you knew about storing overrides in your own Management Pack and need to remove a Management Pack, here's how you can delete a Management Pack that has a dependency on the Default Management Pack. Essentially, you need to export your Default Management Pack, delete both the Default Management Pack and the Management Pack you want to remove, edit (after backing up the file) the Default Management Pack to remove references to the other Management Pack, and then import the clean Default Management Pack.
Detailed instructions are below. In these instructions, the Management Pack you want to remove is referred to as MPToRemove.
Note: This procedure directs you to delete your current overrides and manually edit your Default Management Pack. It's not for the squeamish!
PingBack from http://blogs.technet.com/momteam/archive/2007/05/02/best-practice-for-creating-overrides-for-management-packs.aspx