Schools automatically do insurance for all students; I don't think you can get a refund; they're in a bizarre place where they have to make sure the students are covered, doesn't matter if you have secondary health insurance or not.

I'm quite positive the insurance company knows if you are in school and/or can check. If something happens, you could get in big trouble that way, financially or health insurance way. If you aren't in school you can't pretend you are, that's fraud and they could drop your parents too; don't mess with insurance companies!