Rogue Tenant not vacating property

My tenant is not vacating premises and wants me to reduce rent and give him an eight month extension to stay. He has a very flickering mind and mostly contradicts his own statement. 2 months back he gave me a notice vide sms to vacate citing reason that rent is higher than market value and he can only extend if I reduced rent. I accepted his notice to vacate and asked him to vacate and he stopped paying rent and asked me to adjust rent against security deposit which I declined. Now after two months he comes back and says he cant vacate as he has given the address as his address proof. Kindly advise how much time (worst case scenario) would it take in case I file an eviction sute for illegally occupying my premises and also not paying rent -- case in court. Also are there any benefits of getting the lease deed registered at the office of registrar versus a lease on stamp paper notarized by any authorized notary. Would there be any benefit in extending the lease for next 8 months through lease deed registered at the office of registrar. Would I be able to get the premises evicted faster if there is a lease deed registered at the office of registrar v/s a normal lease deed which is notarized by a notary.