Vinyl roof question

[wilken370Z]

Alright, let me start off by saying thank Everyone who's helped me out with so many projects so far, this forum is very helpful.
Now I bought a 5x4ft gloss black vinyl 3m scotch print for my roof, started getting it I'm the corners but couldn't get the sides to fit underneath of the rubber stripping that's on it, if you guys know what piece I am talking about. Tried just cutting it along the rubber edge but turned out like crap. Tore it off and basically threw $50 in the trash. I bought another vinyl same one, but want to make it easier on myself and just take off the side pieces of the car just above the door, have no idea how to do this but they must come off to replace the windshield so I know they do. I've added a couple pictures of the piece I'm talking about (sorry didn't know what it's called). Anyways does anyone know how to get these off safely or would I probably be better off just going to a nissan dealer and maybe asking them? Thank you guys so much