I don’t leave a thread. I just ignore posts from people that I don’t want to converse with. If it’s posted to me, I check who posted it and if they are trouble, I don’t read it. It takes practice. We are taught from childhood to respond when addressed. But as adults, we really CAN ignore aggravation.
That’s what I do. My mental “ignore” button. My eyes recognize a name of someone who just aggravates and antogonizes, and I skip over their comments. I’ve gotten very practiced at it. Really saves my temper and equanimity.