Soak a clean cloth in vegetable oil.
Rub the cloth over the rust vigorously. If the rust wasn’t very old, this should be all you need to clean the wok.
Scrub the rust away with superfine steel wool if you can still see the stain. Scrub with heavy pressure until the stain is gone.
Add 1 drop of liquid dish soap to the rust stain if you can still see it.
Scrub the superfine steel wool into the rust stain until it is completely gone.
Rinse the area with clear water and dry it with a clean cloth.