Removing a uPVC Panel from a Door

[Rob_Quads]

To the side of my door is a half height uPVC panel. I would like to remove this so I can find out how thick it is to get a replacement panel to fit a cat flap to. I've tried to see if I can un-pop the side strips but can't see how to. I can't even get a knife blade between the two bits of plastic. I am able to slide a screw-driver between the panel and rubber grommet.

Below are a couple of pics showing the panel

Cheers for any advise

 

[xerxes]

Start in the middle of one the longer mouldings; try pressing the moulding inwards with the heel if one hand while inserting a knife in the gap which you should be able to discover between the moulding and the door. I use a worn putty knife with rounded edges for this in order to try to minimise damage, then one or two flat-bladed screwdrivers to open up the gap and spring the moulding away.