Removing a door latch from a Ford Focus car is not an easy task. The latch is part of the complete lock assembly, which you must remove. You need to remove the door's inner trim panel and then the outer door handle in order to then disconnect the lock assembly.
Removing the Door Panel
Disconnect the battery's negative (black) cable before you do anything else. To unclip the cover trim on the door's pull handle, insert a screwdriver into the hole below the cover and twist. You can now remove the screws that are beneath the cover. You will need that same screwdriver to pry off the screw cover and remove the screw within the inner door handle cavity so you can remove the bezel (a band containing a groove and flange). Remember to disconnect the electrical connecter for the window switch that is within this bezel; you will need a small, flat bladed tool to disengage the clip along the connector's inner edge. Now remove all the screws along the outer edge of the trim panel, lift the panel off the door and turn it upwards at the rear to completely remove it.
Removing the Outer Handle
Once the door's trim panel is removed, remove the side impact bolster by rotating it counterclockwise to free it from its retaining clips. You should then pull those clips from the door panel. Disconnect the inner door handle by unclipping it from the front end and sliding it out in a forwards direction. You don't need to disconnect the handle from its cable at this time. In order to peel back the water shield, cut through its butyl strip with a knife or scraper, making sure you don't damage the weather shield, door panel or adhesive. To remove the bezel for the lock cylinder, loosen but don't remove its retaining screw within the door handle assembly, then unclip it. Loosen the exterior handle's screw--on the inside of the door--and then slide the handle back and pull it out.
Removing the Assembly
With the exterior handle removed, disconnect the electrical connector for the door lock motor--you will need a small screwdriver to release its retaining clip. Remove the three bolts on the rear door edge surrounding the lock assembly--these will require a Torx wrench. Unclip the reinforcement bracket for the lock and handle from the door panel, and you can move the assembly (with the door lock mechanism) out of the door through the inner frame. Place the lock assembly on a work top so you can easily work with it. You will need this work top close to the car door since the assembly is still connected to cables. Remove the assembly security shield by unclipping the trim in the back and removing the screws. Pry out the locking clip for the remote control rod with a flat screwdriver; you might need to replace it as it can break. Turn the connecting rod a quarter turn to unhook it from the door lock cylinder lever, unclip the outer cable from the lock housing and give the inner cable a quarter turn to disconnect it from the door lock linkage.