Hi, they tap on/off. They're a tight fit but push sideways onto the lugs which are fitted to the door. I think (and please go gently in case I'm wrong! ) that they are tapped on from the front of the door (so you will need to tap them from the back of the door to get them off). I use a wooden mallet, and/or some soft wood to avoid cracking the plastic.
As above I have found it better to have door open so it does not bump into the trim on the front wings. A strong tap from the palm of my hand is offten good enough to remove the door bump trim and no damage to paint.