The door trim can be removed, but you have to remove the entire door panel - I learned this while I was installing sound deadening. The colored trim has 6-7 screws on the inside of the door panel that have to be removed, and then the trim easily pops out. I took my trim to have it color-matched at a local hardware store, so that I have it for painting parts/accessories for future projects.
I used a YouTube video for reference, but the door panel comes off after you remove 3 screws (2 under the window controls - window controls pop out with a bit of force, and 1 behind a small plastic cover behind the interior door handle).
As far as the trim on the dash is concerned, I can't help you there. My guess is that it's a real pain in the rear end.
Yeah, I fudged my username. I subconsciously wanted a a "GT-R", and not a "C-HR".