You pour the product in, wait for it to dissolve the blockage, and then flush the drain with running water. Be aware that some chemical drain cleaners can damage the plastic or rubber parts of a garbage disposer and cause injury if the cleaner splashes into your eyes or onto your skin. If the blockage doesn't clear after a couple of tries, you're ready for a more hands-on approach. Some traps have a clean-out plug that you can unscrew to access clogs. If yours doesn't have such a plug, remove the entire trap and scrape out any material that you find there.
Sink traps are easy to remove.
To protect the chrome finish on the slip nuts, wrap tape around the jaws of your wrench or pliers. Clean any blockage from the trap and then reassemble the trap. Tighten the slip nuts with your hands first, to be sure that they are threaded on the trap correctly, and then tighten with the wrench or pliers. Some folks may advise you to try unclogging the sink drain with a plunger before you resort to removing the trap. We believe that cleaning the trap first is a better approach, because using a plunger can push the clogged material out of the trap and further into the drainpipe, where it's more difficult to remove.