Drain Water and Remove Old Valve

What happens here

After successfully shutting off the main water supply, open an existing faucet inside the house (preferably the one the T-stop valve will serve) to relieve any residual water pressure and drain the remaining water from the pipes. Next, go under the sink where the work will be done. Use an adjustable wrench and channel lock pliers to carefully loosen the compression nuts and remove the existing angle stop valve from the stub-out pipe. Be prepared for a small amount of residual water to drip out, so have a bucket or towel ready.

Goal: Remove the existing angle stop valve and clear water from the line.