Can I give back my Master's Degree and remove my Master's Thesis?
You're in a tough situation. If the university is smart and if the Title IX Coordinator has power (big ifs), they will do everything they can to keep you from suing or otherwise bringing bad publicity to the university. This could include finding a way to count your Master's research to your dissertation.

I infer from your reference to Title [IX] that you are in the United States. I recommend that you look into the Legal Advocacy Fund of the American Association of University Women (whether or not you are female, which you don't state). They might be able to offer you some free advice or point you to a lawyer who can give a free initial consultation. It is possible your university will be more cooperative if they know you are well informed.