If someone is breaking the rules, what you can do is flag them. Once flagged, a moderator will eventually come along and remove comments that are not nice, spammy, etc. Unfortunately if it's just because you don't like what they said... there's little you can do besides: You can also delete the Instructable and then post it again, but this is likely to just give them another opportunity to bother you again. It's also fairly annoying to loyal instructables readers who keep an eye on what's new. I'm sure the staff doesn't enjoy it either. But it works.