UPVC Door Frame Trimming

[nabby68]

Hello
I’m looking for some advice regarding my porch.
It was built before we moved in with quite a large height difference between existing house floor and porch floor. The height difference is about 60mm and is a slope not a step.
I would like to raise it so its level with existing floor but I’m governed by the front door threshold as the porch floor is only 10mm below door threshold. The option I have is to remove the whole upvc frame and lift it up as there is about 45mm head room above door frame. Would it be possible to shave another 15mm off the door frame to give me the rest of the height. I’ve attached a couple of pics to help
Thanks

 

[crank39]

There are small ribs on the outer edge you could cut off to gain another 10mm ish, so long as the door won't foul the head when opening and the fact you'll lose a lot of frame showing inside and the height difference looks wise outside but that's just asthetics, if it's a one piece cill outside you'll need to leave that down and fit a frame extender between the cill and door, technically it can be done though