Well if they're not paying rent that's reason enough to kick anyone out- I had a roommate who was similar, but still wasn't even the worst roommate I ever had. Just call a house meeting and tell her she has to leave- It's okay! You don't need to list any reasons- just give them 30 days and say you have all decided it's not a good fit and you'll be looking for someone else (or better yet, have someone already lined up). That's all! It's best to not go into specifics because it's not a discussion. (And keep your cool no matter what!) Everytime I've done this the person ends up leaving early. Good luck! You'll all be breathing a big sigh of relief when she's gone.