Roof Entrance locked by Top floor owner in multistoreyed building

I am living in a builder floor in which 4 floors are constructed as per Delhi municipal Act which governs it. Owner of Top floor have roof rights as per his sale deed and he is restricting us to go to roof for cleaning water tanks by putting a lock to such gate. We have made various complaints to Delhi Police regarding same however police has submitted action taken report against our RTI stating that owner of top floor has locked entrance of terrace for security purposes and he does not have any objection in case you want to get your water tanks cleaned. Actually there is no evidence that he is not allowing us and Police is closing complaints. My questions are mentioned below: 1. Is the owner of top floor right in putting lock at entrance of terrace where water tanks of all other owners are kept? If not, under which section and Act we can file complaint against him and to which authority?