How do I change a major for the UC application after the due date?

I need to change my UC Davis from Biomedical Engineering to another major and my UC San Diego from Bioengineering: Premed. I looked at the site and it only addressed people who wanted to add a school, not change a major. How can I do this and what format should I use?How do I change a major for the UC application after the due date?
You don't have to pursue the major that you chose on your application. You can change it when you get accepted to that university.