Struggling to remove beading on door

[Daved27]

So I'm trying to remove the beading of the glazing on my new rear UPVC door, because it's currently glass, and I want to change it for a UPVC panel with a cat flap (so when we go to sell the house, I can swap out the cat flap panel for the glazing again)

From how-tos online it looks like it should be easy, but a combination of the fear of mangling the beading, and the beading being very tight has got me stuck.. I just can't seem to get it off. I purchased a moon knife for the job, but that's even thicker than the scraper I was already using..

I suppose I'm looking for a sanity check, because I feel like I'm already butchering the beading but getting nowhere.. how should I be trying to remove this?

Pics of beading, one showing my mangling:
https://imgur.com/a/mqYQgxK

Do I just need to be more.. violent? Any tips?

 

[footprints]

Start in the middle of a side, it can flex more than the mitered corners.

 

[Viscous]

Did you manage to solve this @Daved27? I'm in basically the same situation as you were. My beading looks identical; I bought the moon knife and gave it a bit of a butchering but couldn't get it off either . I tried starting in the middle of the long side but still can't get the beading to pop out, even though I can kind of get the knife in.