I wanted to add that to, but now I've voted on it. I really like to get this done, as it just sucks that there isn't a supported method to do anything about it.
Either sledgehammer: delete the computer record or editing SQL, which is what I would need to do Maybe you guys can give that a push; https://configurationmanager.uservoice.com/forums/300492-ideas/suggestions/8 389383-ability-to-change-approval-requests-from-approved
