These simply pull out from the top. If it is really difficult, you may want to do this after you detach the master cylinder from the car. After all the brake lines are removed, then loosen the two nuts that hold the master cylinder to the car. The studs that stick out of the chassis are directly attached to the pedal cluster inside the cockpit. After the master cylinder is removed, the car should look like Figure 3.
Installation is a bit more difficult than removal.
The tough part is getting the reservoir fittings to properly seat into the new master cylinder. The new master cylinder should have new rubber boots that surround and secure the reservoir lines. After doing this twice, I have not yet figured out a completely painless method of inserting the lines into the master cylinder. If you remove the rubber grommets from the master cylinder, place them on the ends of the reservoir lines, and then insert them into the master cylinder, you can usually tell if they have slipped, or if they have seated properly. The toughest part seems to be getting enough leverage when your crouched underneath the car.