Joint tenancies can only be ended:

• By death.  When one joint tenant dies, the remaining tenant succeeds to the sole tenancy.
• By court order.  Interest in a joint tenancy may be assigned to one of the joint tenants by court order as part of divorce proceedings, dissolution of a civil partnership, or order under the Children's Act.
• By notice to quit.  One party to a joint tenancy may give the Council Notice to Quit. This will end the tenancy for both/all tenants.  The Council has discretion whether or not to offer the remaining tenant(s) a new tenancy.   If agreed the remaining tenant(s) should sign a new tenancy agreement.  This is the correct way for dealing with a joint tenancy where one of the joint tenants is offered another Camden Council property. 
  
  Terminate the tenancy on Northgate and create a new tenancy in the sole tenants name.  Remember to tell the estate parking and access team if there was a non residential letting on the joint tenancy.
• NEC guides on various NEC processes can be accessed here.