Ending Lease and adding new tenant/lease

I set a move out date for the prior tenant. He no longer shows as tenant in the summary. However, when I add the NEW tenant, she appears as co-tenant with the old tenant still there as primary. This also adds the new tenant on the old lease. I need to keep the records of the old tenant, but end his lease and start a new lease with the new tenant. I am unable to see how to do that.