Open Question: California Corporation Closing or Changing names?

I sold a small Corp to someone, part of the agreement was that they would change over all the names on file with the gov, so far they have not, now Im getting notices for renewal since its still in my name. What can I do if this guy never does his part in changing over. Can I just close the Corp myself, but risk getting sued by him saying I closed his Corp or can I put his name and address on in myself. Help