The ZL button can be removed once the red circled screws are removed.

The L button is underneath the ZL button and is easily removed once the ZL button is out of the way. There is a small hole that one end of the L button fits into.

Remove four PH0 screws, two that hold in the ZL button plastics and one on the top button board and one of the two screws securing the main motherboard.

Warning: Do not try to remove the top button board before you remove this small button board in the next step.