I generally tell my staff to move threads/posts to a hidden staff only forum called "Trash Bin" then admin's are responsible for the final deletion (unless the post was made as obvious spam).
In UBB.Classic we had a mod for "Trash Bin Forums" whereby the delete would simply move the thread to that forum by itself. In Threads I'd say, if it ever made it as a feature, that posts/threads have a new cell in the database table for "deleted" and then mods can mark things for deletion and it'd simply put a 1 in that cell and then a CP entry (like post moderation) would be triggered for an admin to make the final call; but that's a pipe dream at this point of that ever being an official feature.
