Most people keep the included shelf mounted to printer.   When you do this it sticks out approximately 12" from wall.   Printer and printer paper tray may stick out past the 12"

However you can detach shelf from unit and mount shelf directly to wall.  shelf itself  then sticks out only 10" and yes the USB cable still reaches.    Printer and printer paper tray may stick out past the 12"

Also the unit alone (without printer tray attached) sticks out about 8.5 inches from wall.