Knockouts are part of every new sink unless you order one specifically with the knockouts removed. Save money and purchase a sink with knockouts. They are easy to remove if you know the process. Your new sink will have a knockout for a drain hole in the bottom of the sink and knockouts along the top edge for your faucet, possible soap dispenser and sprayer. The manufacturer of your sink scores and marks the areas for the knockouts so they are easy to identify and remove.
Position your new sink upright on a stable workstation, such as a workbench or floor. Turn the sink so the ledge with the knockout marks is facing toward you.
Locate the knockout area and determine which ones you need for your faucet and other accessories. Possible markings for the knockouts include stickers on the ledge of the sink or score marks in the sink's surface.
Position a punch or nailset in the center of the knockout. Hit the punch or nailset firmly. Repeat the process until the knockout has been removed.
File the edges of the knockout with a half-round or rattail file until the edges are smooth. Additional filing may be necessary to make the knockout hole large enough for your faucet and accessories.