[kh99]

You know, I just thought of something (and this applies to TheLastSuperman's solution as well) - you can't just replace all 2's because someone could have a usergroup 12, or 20 something. I think you'd need a regular expression to match ^2, and ,2$ and well as ,2,.

Edit: I guess what I should say is that I think it will work for a one-time removal of some secondary groups if there's no conflict as is mentioned above. For instance if you want to remove secondary group 9 and you have less than 19 usegroups, it'll work fine.