The only legal way I know of to have this money count as a parent asset for your FAFSA EFC is to liquidate the UTMA and invest the funds in a student-owned 529 account. You can’t just take this money and put it in a fund in your name, because, you know, it’s not your money.
Do you mean file financial aid paperwork as an independent? Vey likely that can’t be done.
You’ll only be taxed on the gains, not on the whole amount, and since it’s your kid’s money it will be on your kid’s tax return (the kiddie tax will likely apply, however).
You’ll have to run the numbers under different scenarios. Is liquidating and taking the capital gains hit worth the lower asset assessment that would apply to a 529 account?