Identifying window bead and best way to remove

[Hoponline]

I had 2 windows fitted 2000 ish whose glazing units need replacing as they are misted- I can usually take the beads out easily but these are being a bit of a mare
Can anyone please identify and tell me the correct way to remove as I've had to butcher the 2 sides to remove and don't want to repeat for the other - thanks

 

[Wayners]

Identify which strips are mitred as two are and two are not.
Mitred strip comes out first.
Plastic double glazing shovel tool helps Vs metal scraper.
Unfortunately some old plastic can be brittle a bit stuck in.
Helps to cover in tape and hit it to break seal before popping out.
I'm not great at it's either but that's the idea..

 

[Hoponline]

Thanks for the reply
If it's mitred first then that means pushing against the glass - which is counter intuative - but explains why I had such difficulty
I can fabricate a tool to do this like Soubers and give it a go

 

[Wayners]

Mitred beads comes out first.
The other two are held in by the two mitred beads.
Knocking first with free up though by breaking seal