That's the problem- once something is public, it's public. You could delete YOUR copy, but if the troll or trolls who said something bad replicated it it is out of your hands.

That was the prob with my friend's show. He knew it would go out all over our neighborhood; if you're on public access you kind of expect that. But he had no power over others replicating it, so it got huge youtube notice due to trolls putting it up specifically to laugh at.