I've got loose trim pieces from a W115, the lower ones that fit front and rear glass. They are kinda "C" shaped, with a lip underneath that goes into barbed clips that attach to the body. Looks like these pieces come off by making sure the ends are loose and pushing them to the front (front trim) or rear (rear trim) of the car. Pics of the underside of a RH rear trim piece attached for reference, just in case.
As for the A-Pillar trim on the inside of the car, it's held in place by those barbed clips too, and it looks like you need to pull them back to remove. I attached a pic of the steel backing of a LH side trim piece and the spot where the lower clip attaches.
Sometimes seeing what's underneath is helpful, FWIW.
