Removing sealant around UPVC windows

[Psyclist]

Can anyone tell me what is most commonly used for sealing around the edges of UPVC windows?

I had assumed it is just silicone, but I'm having real difficulty digging the stuff out from around my windows (it has retracted and there are gaps around all my windows making the house draughty) it is just so hard and rubbery. I've tried my sharpest knives and chisels and they're barely touching the stuff.

Any ideas?

 

[Gazman16]

Normally low modulus neutral cure.
Try cutting all the way down the side of the window with a sharp Stanley then using a sharp chisel and hammer on the brick/rendered edge