Can the side plastic on the bumper be removed? well thank you. Because I just want the black bottom. Or is there a diffuser? on the rear bumper. Well thank you.

Looks like you have/are looking at the monte carlo version, a dressed up fabia. All the trim bits can be bought separately, and there are no monte carlo specific bumpers/side skirts, which suggests they just stick on.

A hairdryer and alcohol may or may not help. Be aware that the bumper plastic is very thin and the glue may take the paint with it.. not worth it