There is no way general way to disable layers in MAME. If you are lucky, some of the games will display tile maps in the F4 mode, but most don't. With Crack Down and Bonanza Bros I was fortunate to have the tile maps. However, when it came to Momoko 120%, and Street Smart, I just had to assemble those from scratch. I had to remove the status bars by overlap and some editing.
As you know, F4 enters the graphics mode, enter switches between palette, sprites and tile maps if available. Square brackets ([ and ]) will move through multiple palettes/sprites/tile maps.