Unhook the Plumbing

• Turn off the water supply from the two valves under the sink. Disconnect the valves with your pliers by unscrewing the nut just above the valve. Put a bucket under the sink trap (the u-shaped pipe directly under the drain) to catch the water that's sitting inside it. Remove the trap by unscrewing the two wide nuts holding it on either end. Dump the water into the bucket. Stick a rag into the drain pipe from the wall to block sewer gases until you reconnect the new trap.
  
  

Remove the Sink

• Use a screwdriver to unscrew any brackets holding the sink in under the countertop. Use a razor knife to cut away any caulking around the sink. Lift the sink out, taking out the faucet and faucet handles with it. If the sink and countertop are one piece, the whole piece will have to come off, and may require removal of additional screws, trim, and caulk to get it out. If it's just the bowl that comes out, it should lift directly off the countertop.
  
  

Install the Sink

• Install the faucet and handles first, with the bowl (or bowl-and-countertop single unit) sitting on its side. Put the fixtures through the holes, seal them with the proper rubber flange or plumber's putty according to the instructions. Tighten the mounting nuts on the bottom. Run a bead of silicone caulk around the edge of the cabinet or countertop where the sink will drop in. Lower the sink in. Secure it underneath with its mounting brackets. Reconnect the sink trap and the two water valves. Turn on the water.
  
  

Pedestal Sinks

• Pedestal sinks should be supported by temporary wood braces put directly under the bowl for both the removal and the reinstallation. This will allow you to pull away the pedestal while the bowl is still in place, so you can easily get at the valves and trap underneath. The new bowl mounts directly to the wall, then the plumbing is reconnected, and finally, the pedestal is slipped in underneath it. It's a good idea to have a helper to steady the bowl for you as you work.