Hi
The plates are glued. Usually heat or cold helps to make glue „weak“. You could try to warm up the plates and the inside of the game case with a heat gun. But be careful not to heat it up too strong. Or maybe it helps if you stick the game case into the freezer for a few hours.
In both cases it's better to dismantle the game (removing the game case from the rest such as screens and electronic) first.
After treating the face plate / game case with heat or cold, gently try to lift up at the corners.
I never have tried above solutions, so try at your own risk!