To remove the lock cylinder you will need a small screwdriver. Use it to press down the tab inside the hole at the top of the lock assembly.
While pressing down the tab with the small screwdriver, pull the lock cylinder out. This is made easier if you have the key inserted in the cylinder. But like this door, the key wasn’t available. Without the key the tumblers won’t fall and you may have to wiggle the cylinder out.
Once the cylinder is removed you do need a large hex drive to remove the lock bezel. Pehaps someone knows the size hex drive to use? I’m sure a locksmith would know. I have had luck with a large screwdriver. But you must be careful not to bugger up the inside of the lock.
