It sounds like you have a flat surface pump that sets on the basement floor, and you want to be able to turn it on without walking through water to do it.
You could run a heavy duty extension cord from the pump to the top of the stairs and plug it in when you needed to. But remember electricity and water don’t mix, so the cords must be off of the floor.
Otherwise:
Shut off the power to the outlet.
Open the outlet box and find the black wire that feeds the outlet. It will be connected to the narrow blade side of the outlet.
Disconnect the black wire, and connect it to the black wire of the 12-2w/gnd or 14-2w/gnd sheathed electrical cable that you will run to the switch box upstairs.
Connect the white wire of the sheathed electrical cable to the outlet terminal that you took the black wire from. Paint the white wire black with a permanent marker.
Connect the ground wire to the ground wires/terminal in the outlet box.
At the switch box upstairs, connect the black wire to one terminal of the 2-way switch you purchase and the white wire to the other terminal. Also mark this wire black.
Connect the ground wire to the switch box.
Install/replace the cover plates.
Turn the power to the outlet back on.
If you are not comfortable with doing this and are not familiar with the basic codes/regulations I would suggest you have an electrician do this.
ALTERNATIVE: Purchase one of the new remote control adapters for the outlet, and you could turn it off/on from the top of the stairs.
Good Luck!
Dodgeman
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