What can I do if my sister refuses to vacate my property?

My grandfather (died) settled his property to his two of his daughter, elder daughter and younger daughter. The front portion of building to elder daughter and back portion to younger daughter, it is done through registered irrevocably settlement deed. He gave life interest to his wife ( grandmother) ( died). His wife ( grandmother) was living with elder daughter and family in front portion. And the younger daughter was living with her family in the back portion. One outdoor bathroom and room which very clearly belongs to the area of younger daughter, was been used by grandmother when she was alive and elder daughter was using it , since that time grand mother was alive and has life intrested the younger daughter left it, after the grandmother died a month back the elder daughter is still using it and put a lock and refusing to give the portion. So what should we( younger daughter do) we younger daughter are absolute owners now and title owners with all proper document and patta.