Question: how do you change your last name?
Answer: calling 1-800-461-2156 for all of North America (areas outside of Toronto), 1-416-325-8305 in the Greater Toronto Area and Internationally or 416-325-3408.
or, sending a written request to: ServiceOntario. Office of the Registrar General. P.O. Box 3000. 189 Red River Rd. Thunder Bay, ON. P7B 5WO.