How to get a property vacated if tenant refuses

I have a shop in Kolkata which is in salami.The bill is in the name of my father and my grandfather.In 2012 my father and my grandfather has done a leave and licensed agreement with a third party after taking a verbal permission from the landlord. The contract was of 36 month, on expire of 36 month my father had verbal contract with the 3rd party again for 36 month, all this time my father gave him a receipts of licence fee.Now the verbal contract also came to an end on 31.03.2018 Now wen we r Asking him 2 vacant the space is not dng He is Showing his political power and money Kindly suggest me what are my father rights Wat are the legal complications