How can I recess an electrical outlet that protrudes from a glass mosaic tile wall?
Generally, it is possible to turn off the power, remove the switch, and then cut the nails that are holding the box in place (a recip saw can do this if you are careful). You can then drill holes through the box, push it so that it is flush, and then screw the box back to the stud.

This is fairly finicky work.