For the most part Community Managers need to think about forums and comment sections as a holiday party with your friends. You invite them over to share stories, talk about your day, laugh, debate and generally try to have a good time. Differences of opinions are bound to happen and someone might poke a bit of fun at someone else, but all in all it should be an entertaining and engaging event at your house.
So what happens when one of the people at your party starts insulting and degrading another person? You – or someone – would step in and say “Hey! Calm down, there is no need to be like that”, and try to smooth things over so the party can continue. However if this person cannot stop the bad behavior and disrespecting of the other guests, chances are you will step in and say “Look, you need to stop or I’m going to have to ask you to leave”.
Hopefully they get the message. If not, you show them the door.
The same should apply to your forums and comment areas. Debate is fine, criticism should be constructive, dissenting thoughts should be respectful and above all, common decency should be shown to others. If this isn’t happening, then you first reach out to the offender and ask them to stop. Maybe ask them to “Be the better man” and let the heated conversation go. If that doesn’t work, let them know that you will take action if things don’t change and then stick to your guns and remove them if needed. Just be sure you always communicate with them about what you are doing and why you needed to take that step.