Once you turn 18, (or 19, in some states) you are free to do whatever you want, regardless of your parent's rules. If you live under their roof, of course, it's a different story. However, what you are asking for in terms of dating, is not unreasonable.
You're going to be 21 soon. Talk to your parents and tell them (respectfully) that you're going to live your life the way you wish. Because it is YOUR life, and so far as we know, you get one shot. That's it. Be young, have fun. You should be able to date whoever you want, whether they have a degree or not.
Believe me. You'll eventually get fed up and will leave.