Use a punch or a drill bit (blunt end), and tap with a hammer from the top down... the pin will emerge from the bottom of the slide and the extractor will then make it's bid for freedom. Be sure to have a finger holding it in place to restrain it and safely remove it and it's spring.
To replace, use a "slave pin", which I generally make out of a length of Q-Tip. Insert the spring and place the extractor in place, then push in until you can insert the length of rod and hold it in place as you tap the pin back up from the bottom of the slide to the top. Remember to push the pin up far enough so it's just below the level of the inner slide to avoid scratching the aluminum frame during slide travel.