Tenant not vacating the flat

I rented out my builder flat in Crossing Republic, Ghaziabad in May 2013 for 11 months (upto 30thApril2014). The rent agreement was prepared by a property agent on Rs. 100 stamp paper, duly notorized, signed by me only (property is in joint names of me and my wife) witnessed by two persons with a police verification From. After completing 11 months period as everything was O.K I did not renewed the rent agreement in time. The lessee himself purchased the stamp paper wherein purchaser name is PC Nautiyal instead of R C Nautiyal and purchased on 28.7.14. The agreement was for 1.5.14 to 31.3.2015 executed on 30.7.14 (attested by Notary). The agreement is not witnessed by anybody, only signed by me and lessee. No rent agreement renewed after that because I had to sold this flat in July 15 which I already informed the lessee and requested him to vacate the flat but the lessee is neither vacating the flat nor pick or respond my phone calls. I am living in Delhi. When I visit personally he inform that he is searching a suitable flat but actually not in a mood to vacate the flat. Please advise the steps I should take. ............ Ramesh Chander