Step 4 · Remove the Old Angle Stop
This step requires two wrenches. Use one adjustable wrench or a pair of channel-lock pliers to grip the body of the old angle stop firmly. This is crucial to prevent the copper pipe from twisting, kinking, or breaking inside the wall. With a second adjustable wrench, grip the large compression nut that connects the valve to the pipe stub-out. Turn this nut counter-clockwise. It may be very tight and require significant force. Once you break it loose, you can unscrew it the rest of the way by hand. Slide the old valve straight off the pipe.