Does senior citizens need NOC for constructing western toilets in a rented house?

We are living in an old four storey building which has Indian style toilets. The landlord of the building has died. We want to build western toilet in the house but the govt licensed plumber says its possible after getting NOCs and other documents from the landlord and person who has occupied the room below us. Has the govt passed any regulation stating that there is no need for such NOC for senior citizen's? Please help.