If you don’t have a disposal, you can use a caustic, powerful drain cleaner if there is some movement to the water.
Read the instructions.
Once the sink is empty of water, the first thing amateurs do is remove the trap to clear the clog. Don’t bother, because the clog is in the drain line that runs from the sink to the stack. It is usually a 6-foot, low pitch, 1 1/2-inch steel pipe that is filled 85% with layers of grease, soap and food waste that is the consistency of jello.
To use almost any drain cleaner start with small amounts of 1/3 dose first, then chased immediately with 12 ounces of warm water (if allowed on the directions, if you are unsure use cold water.) This is to push the drain cleaner out of the trap and into the drain line where the clog is sitting. Keep your face away from over the sink drain because of splashes. Once that dose settles, do it again, then another. The 3 doses should be covering the entire 6-foot line and begin dissolving the clog from the top down. Wait the maximum time and flush with hot or cold water as instructed. Once the line appears to be clear put the nasty caustic drain cleaner away and now treat for 3 or more days with an enzyme drain cleaner to finish the job.
If you do have a disposal, use an enzyme drain cleaner because it won’t damage the disposal seals. These cleaners are the safest, but are also the slowest in opening a drain line. They are available in liquid and powder form, though I believe the powder is a little stronger.
I make a double dose with warm water and pour it into a running disposal to coat the walls of the grinding chamber. It works by slowly ‘eating’ some of the clog each application. So to get results, it needs to be applied at night so it can work on the clog undisturbed for at least 4 hours.
To maintain the drains with enzyme cleaner, mix a dose of powder into a 16 to 20 ounce container of warm water. Let it sit a minute and pour into the drain.
It will double as a sweetener to reduce odors as it cleans food off the inside of the disposal and drain pipes.