Patio doors are a convenient, easy way to access the outdoors. Usually located in the kitchen, the sliding door saves space by moving left to right instead of back and forth. Security locks on patio doors are often rudimentary and easily removed. A cylinder lock requiring a key is more secure than a simple latch twisted left and right to lock and open. Removing a cylinder lock takes only two or three minutes and requires up to three screwdrivers.
Open the door and have someone hold it steady. Remove the two screws on the inside face of the door lock and pull the face plate off with your fingers.
Remove the one or two screws on the lock plate along side the edge of the door and pull the lock plate off with your fingers. This is where the latch comes out of the door to attach to the hook in the door jamb.
Examine the lock mechanism inside the door carefully. There are two little screws that need to be unscrewed just a twist or two. You do not want to unscrew these all the way.
Pull the latch out of the side of the door with your fingers after the two small screws are loosened. Pull the outer faceplate off from the outside of the door. You now have removed the complete lock cylinder from the patio door.
After inspecting the lock and oiling it if necessary, reverse the steps to put it back into the door. Do not over tighten the small, interior screws.