This is a very common situation and there are 2 ways to address it.  1) You can replace your current roommate with a new one: This new roommate will need to fill out a complete application, send in their most recent month of paystubs and 2 forms of ID to be screened.  In the case they are approved a change is made.  2) You want to keep the unit by yourself: You will need to send in your most recent month of paystubs showing that you can afford that unit by yourself.  If approved, then your roommate will be removed from the lease.  In both cases the security deposit is handling between the roommates as the office won’t release any deposit unless all roommates move out.