The drain stopper in your bathroom sink operates with a lever or pull stick behind the faucet spout. The lever connects to the stopper through a couple of rods under the sink. To release the stopper in the bathroom sink to make repairs or clean it, you will need to remove the mechanism that connects to the stopper in the drain line. Releasing the stopper is not difficult and will only require one hand tool.
Pull up on the stopper handle behind the faucet. The stopper handle is the lever that moves the stopper open and shut. The stopper must be in the shut position.
Go under the bathroom sink and remove the contents of the cabinet. Place a bucket under the sink trap.
Locate the pivot arms that connect from the bottom of the faucet to the sink drain tailpiece. The arm that connects from the sink drain to the clevis below the stopper handle is the pivot rod.
Turn, using channel-lock pliers, the nut that secures the end of the pivot rod into the sink drain. The bucket is for catching any residual water that may be in that portion of the drain when you release the nut.
Pull the pivot rod out of the drain slowly. You will see a ball toward the end of the pivot rod. The ball is what the pop-up stopper rides on to move up and down.
Go back up to the sink and pull the drain stopper out of the bathroom sink.