Brake MC pushrod

There is a tapered piece of plastic that fits around a groove in the pushrod that retains the rod inside the bore of the master cylinder. You will need to pry with enough force to overcome the retention of the tapered piece of plastic. Make sure your new master cylinder comes with the tapered plastic piece, because you will not be able to reuse the old one.

The way I like to do it is to place the rod loosly in a vice with the aluminum piston resting on the top of the vice jaws, the put a big screwdriver through the loop of the rod and smack the screwdriver with a hammer to break the retainer clip.