How to Remove a Bathroom Sink
Removing a bathroom sink is pretty easy, especially if it is a drop-in sink. A drop-in sink drops into a hole in the countertop, rather than mounting to the countertop from underneath the counter (called an undermount sink).
Start by turning off the water to the faucet via the angle valves under the sink. Open the faucet to relieve the pressure and remove the water lines from the faucet. A basin wrench helps if the space is small, but you can use any wrench that removes the nuts from the faucet.
Next, disconnect the drain. You can either remove the sink from the tailpiece (the vertical section of drain coming from the sink) or you can disassemble the trap and remove it that way. Either way you do it, you want to be able to pull the sink out without it getting hung up on the drain.
The sink will be held to the countertop with either clips from under the sink, or by adhesive. If you have clips, they will unscrew from below and free the sink. If you have adhesive, you will have to be careful not to damage the countertop. Adhesive will pull up ceramic tiles or laminate, so make sure you cut through it with a blade before you start lifting. Once everything is free, you can use the faucet as a handle and gently lift the sink from the hole.