N542NG is taken. It's currently assigned to a 2015 Pilatus Aircraft Ltd PC-12/47E registered in Stuart, FL.
See the full aircraft record →A tail number only frees up if the owner deregisters the aircraft or moves it to a different N-number — and even then the FAA holds it before releasing it to the public.
N542NG has been worn before. Past registrations from FAA deregistration records:
Tails one nudge away from N542NG that aren't assigned or reserved: