No. The tenancy does not end until all tenants give the landlord possession of the property back. Subject to the landlord agreeing for one tenant to leave, a new applicant will need to be referenced and new AST’s will have to be signed by all tenants and the deposit will need to be paid and protected. Furthermore a new inventory will be required.
The costs of the above will lie with the tenants.
Where there is more than one tenant, all obligations, including those for rent and repairs can be enforced against all of the tenants jointly.