How to remove Glass/Digitiser from plastic frame?

Hello,

I am trying to fix some Control4 screens which are basically tablets. The main parts consist of the plastic back, the LCD screen, the Glass/digitiser and the thin (1cm) plastic frame that attaches to the Glass/digitiser. The LCD screen and Glass/digitiser are not glued but the thin plastic frame around the outside is glued to the Glass/digitiser (which I have a replacement for.

Im not trying to separate the LCD screen from the Glass/digitiser as that’s not glued, its just the thin 1cm bessel that goes around it which is hard as most of the screens are cracked.

And ideas? I tried using a hairdryer but it didn’t do very much. Maybe I need to keep heating it longed?