Unplug the kettle and let it cool completely
Empty any remaining water
Fill the kettle with equal parts white vinegar and water
Boil the solution or let it sit for 30 to 60 minutes
Pour out the solution
Scrub any remaining scale with a soft brush or sponge
Rinse the kettle thoroughly with clean water
Fill with fresh water and boil once
Discard the boiled water
Repeat rinsing if needed until the vinegar smell is gone