Terminate Guardianship - My parents over my 15 year-old son.

The Courts did not order my son removed from my care. My son did not want to move from the SF Bay Area to Chico, CA when my husband and I moved. I appointed my parents as legal guardians for convenience and not because I am an unfit parent.

My parent's are forcing my son to participate in their religion, he is miserable and they are saying that I can't do anything about it. I need to legally terminate any control they have over my son and I don't know where to start.

Most recently, my parent's have told my son that if he wants to spend time with me I have to come there and he can't come to my home in Chico. If I would've known that my family was going to behave in the way, I would merely have allowed my son to stay with them and not given them any legal authority.

What are my rights as his mother? My husband and I are not degenerates or drug addicts. We are decent hard working home owners. Please, any ideas would help.