cancellation of leave & license agreement

A leave and license agreement is executed between a Licensor and Licensee. It is registered in the sub-registrar's office also.

However, due to some reasons, both the parties want to undo the agreement. No rent/license fees is advanced, neither any deposit is handed over to the Licensor.  Even physical possession is also not handed over.

How to undo the effect of this agreement.?

Is it necessary to register the cancellation deed with sub-registrar's office?

thanks.