Remove the sink stopper and clean off visible hair, soap scum, and debris
Boil water and slowly pour it down the drain
Pour baking soda into the drain
Add vinegar and let it sit for 10 to 15 minutes
Flush the drain with hot water
Use a plunger over the drain opening
Remove and clean the P-trap under the sink
Use a drain snake or zip tool to pull out the clog
Clean the overflow opening with a brush or pipe cleaner
Reassemble the parts and test the drain
Repeat the process if needed
Call a plumber if the clog remains or water backs up elsewhere