Try to find if they have substance or are just ment to bother you. Unlike many of you, Maybe you could explain what you have backing this other then feelings. This is not a troll comment just saying that you can’t just ignore your problems
What I’d do is lock the thread, then start a chat with the person and politely ask them to take it back and edit the post with an apology or something. If they didn’t, or didn’t respond within a reasonable amount of time, I’d delete the thread.