6 brides for 6 brothers but holy crashing batman

You can delete the hoods by being in a different one at the time then clicking on the Hood menu at the top to switch but choose delete instead.
Just make double sure no one is living there or on vacation (actually in a hotel or vacation home etc.) This should bring the couple that is stuck back home. When your played Sims visit a dorm you can't control them but can only interact with them. You have to greet them at the dorm door just like you would greet a visitor at the home lot.