Replacing garbage disposal w/ straight pipe. What to do with the wire?
Just terminate it in a junction box with a blank cover
Simply attach a junction box (a &quot;handy box&quot; with the appropriate cable clamp will do) to a nearby piece of cabinet frame, then terminate the cable into the box via the cableclamp, land the bare wire on the ground screw in the box, and terminate the remaining wires individually with wirenuts.  Finish this off with a blank box cover, turn the circuit back on, and you're done!