Removing the dishwasher from under the countertop
To remove the dishwasher from under the counter, first UNPLUG THE DISHWASHER or TURN OFF THE BREAKER.
Bail or sponge or vaccum as much water out of the dishwasher as possible.
Remove the kickplate.
Reach under the tub with pliers or a screwdriver and disconnect the water feed tube.
Disconnect the drain from your house’s system. Usually this is easiest at your air gap or garbage disposer connection, or where the drain enters your house’s plumbing.
Remove the screws holding the dishwasher to the underside of the countertop.
If the dishwasher has adjustable feet, set them on the lowest setting possible, especially if there is a lip on the flooring in front of the dishwasher (perhaps there is raised tile, or linoleum or other flooring.) Make sure there is nothing sharp sticking out to gouge or scratch the flooring.
Slowly slide the dishwasher out from under the countertop, making sure your drain and fill hoses do not interfere with movement.
Re-installing the dishwasher
Re-installing the dishwasher is pretty much the opposite of removing it, with two things to watch out for.
1) When you readjust the legs, make sure you level the dishwasher. If anything, you want it sloping slightly towards the rear. Too much slope forwards can cause water to slosh over the front door sill. You will also need to raise it enough to reinstall the mounting screws into the countertop, but not so much that the countertop interferes with the door opening!
2) Make sure you plug the power cord back into the correct receptacle. Most dishwashers are plugged into a receptacle under the sink…into the same wall outlet as the garbage disposal. The garbage disposal receptacle has a wall switch…if you plug the dishwasher into the wrong receptacle, your dishwasher may not work unless the wall switch is on!