W.R.T. Section 17(1)(b) which reads as follows:
17. Documents of which registration is compulsory:-
(1) The following documents shall be registered, if the property to which they relate is situate in a district in which, and if they have been executed on or after the date on which, Act No. XVI of 1864, or the Indian Registration Act, 1866, or the Indian Registration Act, 1871, or the Indian Registration Act, 1877 or this Act came or comes into force, namely:-
(a) instruments of gift of immovable property;
(b) other non-testamentary instruments which purport or operate to create, declare, assign, limit or extinguish, whether in present or in future, any right, title or interest, whether vested or contingent, of the value of one hundred rupees, and upwards, to or in immovable property; ............... etc
It is always better to have a registered deed terminating lease in accordance with the clauses in the lease deed.