To replace a Delta faucet, turn off the hot and cold water, disconnect the water lines, unbolt the mounting plate, remove the old faucet and replace it with the new unit. The disconnection procedure for the water lines varies depending on whether the faucet model has a single lever or independent hot and cold water knobs.
In the cabinet under the sink and along the back wall are the shut-off valves for the hot and cold water supplies. Turn them both to the right until they are firmly closed. Place a paint tray or bucket under the point where the lines connect to the faucet to catch any water remaining in the lines.
To remove a single-handle faucet, reach underneath the sink and loosen the nut holding the top of the lift strap to the rod. Slide the metal clip and the strap off of the horizontal rod. Remove the pivot nut and slide the rod out of the tailpiece. Unscrew the water lines using an adjustable wrench. Unscrew and remove the mounting nut from underneath the sink and remove the old faucet. Scrape off any old caulk remaining on the sink mounting surface.
For a two-handle sink, disconnect the water lines, then remove the three mounting nuts. There is one located in the middle and another under each handle. Remove the faucet and clean the mounting surface as before.
Install the new faucet as the old was removed, ensuring to apply sealing putty or plumbing caulk between the faucet mounting face and the sink top.