First of all, you need to turn off the main valve. If you are redoing the toilet plumbing, turn the valve counter clockwise until fully tight. Use the wrench to free the nut.
Now, it is time to work on the toilet’s tank. Loosen the pipe by turning the nut anticlockwise. You may find the old pipes fully damaged. Set them aside, and discard.
After discarding the old pipes, clean the valves. Use a piece of cloth for this. It is always better to wrap the male part of pipes with plumbing tape or thread. This step will enhance the durability while saving you from leakages in the future.
Now, attach the replacement pipes. Turn the nut clockwise until fully tight. You can always use a decorative bronze or silver paper to cover the base of the new pipes.
Turn on the main valve, and closely see the new plumbing. If you find any leakage, tighten the nut further with the help of the wrench.
You can redo the Sink Plumbing by repeating the same steps. After turning the water supply, spread a clean towel on the base of your bathroom sink.