Removing switch that turns on / off the outlet
Turn off the breaker
Remove the face plate.  You should find two (usually) black wires on opposite ends of the switch.
Remove the switch, and join the two black wires with a wire nut.
Turn on the breaker, and test the outlet
Put a blank face plate on the (now junction block)
Install cabinets
Cut a hole in the back of the cabinet to access the junction box.