Remove yellowing on bathroom sink

what is your sink made of? is it acrylic or ceramic or stainless steel?

have you tried Bar Keepers Friend? Its a scouring powder that should work. If it doesn't I would say your stains are soaked in and its time for a new sink.

try The Works tub an tile cleaner from the dollar Store. And get the toilet cleaner while you are there. Amazing products.

Toilet bowl cleaner Lysol Complete it will clean the yellow away

Have you tried CLR cleaner or could be CRL calcium rust on line cleaner

I don't know if you'll be able to get the yellow off. My porcelain sink yellowed where the porcelain is thinly applied. It's actually showing where the sink is beginning to rust. Ours is worst by the overflow hole. I just scrub the sink and know that we'll eventually have to replace it. I guess we're lucky that the damage is where it's not really visible to the casual eye.

Soak a paper towel in vinegar, place it on your stain and let sit for a few hours (unless the sink material manufacture warns you to not use vinegar). Wipe off your stain.

try scrubbing with Bar Keepers.

If your sink is porcelain, then you can use Whitening Toothpaste and an old toothbrush or scratch free scubbing pad. Scrub caefully and the stains will disappear

After using the whitening toothpaste to clean the stains from the sink, Iwipe down my sink with mineral or baby oil to keep them from staining easily. Just a few drops of oil, a paper towel and wipe it down until no oil remains on the towel. I use mineral oil on all my stainless and porcelain appliances, sinks, tubs and showers. It help keep them cleaner longer and it's easy to wipe down quickly. Repeat the stain removal and/or oil cleaning as necessary.

You could also try 1/2c baking soda + 1/4c hydrogen peroxide+1 tsp dish soap. This is my go-to scrubbing cleanser. I keep mine in an opaque squeeze bottle to keep the peroxide from turning to water.

try salt and lemon I squeeze the lemon onto the salt