Removing Father's Name From My Birth Certificate

I live in San Diego California. I'm 20 years old and on April 1, 2008 I had my name changed by the courts to my step dads name. What I want to do now is remove my biological father from my birth record. I would like to put my step dad but if I can't that would be alright. I have had no contact with my biological dad since I was four. My step dad wanted to adopt me but things were tight with money back then. I hope someone can help. Thank You.

You cannot just change your birth certificate because you want to.

Because you changed your name does not change who your parents are. If you wanted your step father to appear as your father on your birth certificate, then he would have needed to adopt you. A mere name change is not sufficient.