Insert a hooked cobblers knife behind the top right where you can lever it away a bit.
Alternatively, use a hooked blade in a Stanley knife to drag it downwards and break any paint or to cut through any silicone sealant that may have been used.
If you manage to get a portion away from the wall put a batten across the opened section to prevent it springing back and sticking again. Continue around the edges moving the batten as you go. The batten will also help to apply light pressure to the edge that you are working on.
A thought to keep in mind. "It went on, it will come off."
Alternatively, use a hooked blade in a Stanley knife to drag it downwards and break any paint or to cut through any silicone sealant that may have been used.
If you manage to get a portion away from the wall put a batten across the opened section to prevent it springing back and sticking again. Continue around the edges moving the batten as you go. The batten will also help to apply light pressure to the edge that you are working on.
A thought to keep in mind. "It went on, it will come off."