I'm on the fence between relinquishing control to the users or maintaining identity. You have to let a forum become what it is naturally, but at the same time you need to protect the reason you made it in the first place.
We have no rules here, but at the same time, if it became a forum devoted to rap music and football overnight, I'd be disappointed Karsten didn't put his foot down and encourage the users to go back to movie talk.
In my specific example, I was a very laid back host, but my intention was a for a general forum where anyone was welcome. This guy had already driven a couple of users away with overly political and racial musings. That post was the only one I removed and I did so because it was deeply offensive. If I left it, then the forum was instantly unwelcome to a huge portion of people. The fact was, he was nothing more than a troll spammer, but unfortunately, other members had a really screwed up idea of free speech.