Typically the panel will be held in with detachable beads.
How to remove beading from upvc door panel.
Replacing a upvc door panel.
I just can t pry away the beading.
I have been trying to remove the beading but i am not 100 certain this is internally beaded but it does look like it.
This will usually be on the inside of the house.
I have used a 1 piece metal putty blade a second blade with a rubber mallet.
Instructions on how to remove a upvc door panel for measuring.