If you're talking about his sig then yeah, I don't think it should have been there.  I don't see it anymore so that's cool.

As far as getting rid of it, all you have to do is edit his sig.  The sig data isn't stored in each individual post (although it's displayed in each post), it's stored in a users table.  So if you change his sig it will reflect on every post he made.  That doesn't mean he can't go in and change it back though.