Step 2 · Remove the Old Strainer Assembly
With the P-trap removed, you can now remove the old strainer. From underneath the sink, use your channel-lock pliers or a dedicated sink strainer wrench to loosen the large locknut holding the strainer assembly in place. You may need someone to hold the strainer from the top side of the sink to prevent it from spinning, or you can wedge the handles of a pair of pliers into the crossbars of the strainer. Once the locknut is removed, push the old strainer body up and out of the sink drain hole.