This should be a pretty basic feature, just not having a private message be there anymore. But for some reason that does not work here?
I tried searching for this. I found a year old open issue on GitHub and some reddit users complaining about this very issue.
Talking with some people in the comments here, it seems like some people don’t understand that one might not want a message to be in their face. Or the idea that just because something could be recovered doesn’t mean we should treat it as an absolute
You can mark them read, at which point they won’t appear with the default “unread” filter on.
If they’re offensive, you can block the user, which will make them disappear completely until you deliberately unblock them.