Hi! In my opinion, you need to file an affidavit for name change, which should include your old name, desired name, and reason for name change. Then have such affidavit attested by your 1st class district magistrate or a notary. Keep extra copies of the same.
Also, you need to send out notice(s) of name change and have them published in any two local newspapers. Then, with the help of the affidavit and the publication, you will need to have your name change published in the Gazette of India.