03 F150: is it possible to remove the mirror embly that folds from the triangular door mount?

You can't separate the mirror head from the mount that holds it to the door. The mirror embly is meant to be a one piece component. If you tried to separate them you would destroy the whole outer housing and then have to drill out the pivot point. Three bolts and 2 screws and a lot of push tabs on the inner door panel and it is off.