In my current school I have yet to notice a situation with trouble parents. Back when I was studying Kenpo however I recall an incident where a mom started going off just outside the doors at someone else's kid over what turned out to be a misunderstanding anyway. Before anybody else could react the assistant instructor was out there in a flash and got between them to diffuse the situation and protect the kid. The mom who had been yelling backed off and went inside after yelling a parting shot at the kid's mom.
The next day after classes our sensei had a private chat with the yelling parent and basically told her that her daughter was welcome anytime at the dojo but that the mom could not be the one to bring her. Later it was found out that that mom got very upset and threatened to beat up sensei! ...But obviously didn't. That was the last anybody at our school saw or heard from that family. A shame, because the little girl had been doing very well and getting along with everybody.
That "trouble mom" in particular had been a problem in other ways before the yelling incident; she had a tendency to be a nasty gossip and was generally very negative. I suspected mental problems personally.
After thinking about how sensei handled it, I think he had been very wise in making it clear that it was that specific mom's behavior and not her child's that was being addressed, therefore it was only the mom who was "banished". I saw the dad come very often to practices, so in theory he could have been the parent to bring his daughter instead, but apparently it was too much of an ego blow for the mom to accept those terms, or perhaps she cooled down later and couldn't bring herself face anybody there in light of her own bad behavior. So, sensei lost that family's business over it, but honestly, if he hadn't banished that mom, he would have lost mine not long after, and possibly others'. IMO he was correct to weed out the bad apple from the barrel so to speak.
I don't believe any of this was prescribed in writing, just the good instincts of how to handle situations on a case by case basis. Kind of like reacting to one's sparring partner who moves without warning; you have to have a good head to keep your balance and still keep adapting to the changing situation.