Termination letters to tenants should contain the date the letter was written as well as the date by which the tenants need to vacate the apartment. It should also include the tenant's current address, as well as a reference to the paragraph in the lease agreement about terminating the lease.
Different areas have different laws related to terminating a lease. When writing a termination letter, make sure that you know how much notice you have to give tenants before requiring them to move out. The letter should also include a business heading with the name and address of the sender, as well as a signature.