I don't know if keeping the usernames visible is a good or a bad thing at this point, but it kinda sucks for insecure people who don't wanna get roasted lol
If so, it's entirely possible to edit the post by crossing out or even erasing all the offensive words and adding or substituting an apology. "I've realized I posted something rude and insensitive here, so I've deleted it and will try to do better in the future."