First, you should swear an affidavit before a Notary and get it attested by him. Give a public notice in a popular newspaper - one in English and one in vernacular - notifying the change of name. Submit copies of these to your employer, together with the amended Aadhaar, PAN, Ration cards, Voter ID. Get them verified by HR and request them to make the changes in service records and nominations as well.
Simultaneously, using these documents, get the amendment in Bank accounts, passport, driver's license, rent agreement, and employee ID as well.