Turn off the water supply and flush to lower the water level if needed
Put on gloves
Pour toilet bowl cleaner or white vinegar into the bowl
Let it sit for 10 to 30 minutes
Scrub the stains with a toilet brush
Use baking soda and vinegar for stubborn stains
Use a pumice stone gently on hard water stains
Scrub under the rim and around the water line
Flush to rinse the bowl
Repeat if stains remain
Clean the bowl regularly to prevent buildup