Photo 2: showing the removal of the retaining screws
In this example it is a two lever lock which has a second bar or bolt with a thumb turn to lock a bathroom or toilet door.
Having removed the one or two securing screws, you then remove one of the door handles. Removal of the door handle allows you to access and then remove the metal bar that runs through the door and the door locking mechanism. Note: the metal bar will often be dirty with an oil like residue, so it is worth having an old cloth or some kitchen roll to hand to wipe this clean. You have to remove the bar in order to slide out the locking mechanism. If having removed the bar, it is difficult to remove the lock then; (1) check that all of the screws securing the locking mechanism have been removed from the edge of the door, and (2) then insert a screwdriver into the square opening into which the bar normally slides and use this screwdriver to slightly move the lock forwards.
Photo 3: showing the use of a screwdriver to assist in freeing the lock
