Failed to pay the rent and evict the premises.

My grandfather had given 1500 sq.yds vacant site to the lessee to run movie theater business for a period of 50 years at the rate of rs.300 rent through the period under a registered lease agreement. At the end of the lease period the lessee has to vacate the premises taking all the movable properties such as projector, fans , tubes chairs etc. now the lease period closes by 2015 October. The present state is that the leases has closed the theater business and just given the canteen to a bar and restaurant. And for last 10 months not paying the rent. As per our registered lease agreement if lessee fails to pay rent for 6 months we can occupy.

Please advice how to proceed as he failed to pay rents and also sublet the premises. As Ours is a joint family we badly need the property as we want to sell and our share of money. being a grandson along with other other grandsons what best step we can can take against the lessee please advice.