You can lose STILLLIKEDRESSINGUP and change your role, just like people on military bases. Change slowly. But if you save the file, you can go back in time, but you can change into a police uniform at the police station.

If you want to change your police uniform, you must complete the Copland task. When you enter the police station, there will be a pink aperture in the room on the left, where Tommy will change into a police uniform. If you don't complete the Copland mission, there will be no police uniform. If you fly a plane, there will be a plane at the West Island Police Station. After killing Sonny, it will appear on the roof of your V-Point building. The quickest and most direct way is to use cheating software THELASTRID.