"10. I'm going to create a new account because I've been marked. Why shouldn't I?
A: You shouldn't create a new account because you marked. You're only allowed one account. If you believe you've been incorrectly marked, refer to point 7. If you really need more than one account, and you're going to use it for legitimate purposes, just ask. You can email email@example.com with your situation."
Point 7 is:
"7. I was marked as a cheater/sandbagger/booster even though I didn't cheat. What do I do?
A: It is possible, though not very likely, that you were incorrectly flagged as a cheater. You can email lichess at firstname.lastname@example.org arguing your case. As in real life, ignorance isn't an excuse for being marked. Again, please don't plead your innocence in the forums."lichess.org/qa/258/all-about-cheating-questions-and-answers