I think you need someone to take all the weight off of them. And then you should be able to just snap them off. There are no special instructions in the Bentley. Every one I have replaced just snapped off, no pins, no screws, but the weight must be off them.
1995 325I, window tint, K&N, debaffled airbox, BMW #104 wheels, Nighthawk low beams, smoked side markers, smoked corners, smoked taillights, M3 stlye heated mirrors, various interior bits, Bosal cat-back.