Turn off the water supply and drain the pipe
Mark the cut line on the copper pipe
Choose a pipe cutter, tubing cutter, hacksaw, or oscillating tool
Place the cutter on the marked line
Tighten the cutter lightly against the pipe
Rotate the cutter around the pipe
Tighten slightly after each full rotation
Continue until the pipe is cut through
If using a hacksaw, hold the pipe steady and cut along the mark
Remove any burrs from the cut edge
Clean the pipe end before reconnecting it