Evan,
Do you have the key for the lock? The correct procedure to remove the lock cylinder requires having the key and the latch in the lock position, key removed. You should then see a spring loaded tang through the small square hole in the bottom of the hatch housing. Depress the tang with a small tool of some kind and insert the key; lock cylinder should then slide out. Without the key there is another small square hole 90 degrees away, under one of the mounting tabs and difficult to get to with the latch in the door, would have to depress the retaining tab and the tumblers one at a time to get the cylinder out intact.
Check your pm, talk soon