Felt Flashing removal?

Hi
I want to cover my flat roof fascia boards with UPVC. At and approaching the corners there is not sufficient space between the felt flashing and existing facia board to slip the UPVC underneath. So looks like I will need to remove the felt flashing.

The flashing was stuck to the roofing felt using felt adhesive 10yrs or more ago. Is there a way to remove the flashing that won’t damage the roof felt.

you could try and warm it with hot air paint stripper and then you may be able to slip it under.

Nice idea but it is very tight on the corner, as in actually touching the wood facia.

So it would have to stretch enough to allow for the extra thickness on both sides of the corner. Too much I think without the risk of splitting which would then necessitate the complete removal of the flashing which I don’t know how to do.