I live in California and was asked to move into an apartment with a friend of mine. There was some tension with the former roommate and they asked her to move out. She agreed and found a place, but supposedly the place fell through so my new roommates agreed to let her stay on the couch for 30 days to give her time to move out. She paid rent until 3 days before I moved in, but her stuff was still in my bedroom when I arrived with movers. She has since moved it all to the living room but is now threatening to not leave unless she gets her deposit. We don't have her deposit, the landlord does, but for some reason she wants us to give it to her.

Is there anything we can do to get her out of the apartment? She is still technically on the lease, but the landlord knows I have moved in. She claims that she will now pay rent to stay in the living room and wants to treat that like her bedroom but doesn't think she should pay any more money than she did for her old room (even though the living room its almost 3 times the size.) She has threatened physical harm against one of my roommates and Im afraid that she may steal or damage my property.

She is threatening legal action against my roommates so any course of action needs to be followed very carefully? What are our legal rights? How can we get her out?

First, in a situation like this, where one roommate is replaced by another, the new roommate pays their share of the deposit to the outgoing roommate. The landlord will only return the deposit when the unit is completely vacated.

Second, if she is on the lease, the landlord has to evict her, Neither of the other leasees can.