Assuming you wish to install better speakers as explained in Part one, Part 2 explains how to remove the factory speakers. The photo shows one rear speaker being removed as follows. Use a blunt screwdriver to pop the speaker grill from inside the trunk. Next enter the backseat with a Phillips screwdriver to remove one retaining screw. Finally, pry gently to lift the speaker.
I don't have an image for the front door speakers. First remove a Phillips screw from inside the door handle. Then pry gently around the lower part of the door to pop the friction fit plastic pins. Next, lift slightly to free the door covering from the plastic lip along the glass. Be careful with the wiring harness which attaches to the door handle switch assembly. The switch cover has a retaining screw. Perhaps you can adjust the door cover to allow access to the speaker without removing the switches. Good Luck!