You can't get it taken off - the only thing you can do is have the debt marked as satisfied/settled once it's paid. You can have notice of correction added to your credit file if something is in dispute but unfortunately the cold hard facts are that once something is on your credit file (I guess unless you can prove that it's an error on the part of the creditor and they can agree to it) it will stay there.

Sorry to be the bearer of bad news but this is a lesson I've learned myself..!!!