You should first refer to the terms of your Lease Agreement.

In most cases, roommates are considered “tenants in common” and are joint and severally responsible for the terms of the Lease Agreement and all parties named on the lease are responsible for the rent.  Check with your landlord to see if you can make arrangements to have another party take your place on the lease.  Prior to signing any lease, it is always a good idea to have a written understanding among roommates stating individual responsibilities and expectations.