Unplug the kettle and let it cool completely
Empty any water from the kettle
Fill the kettle with equal parts white vinegar and water, or use a kettle descaler according to the label
Bring the solution to a boil
Turn off the kettle and let the solution sit for 15 to 30 minutes
Pour out the solution
Rinse the kettle thoroughly with clean water
Fill the kettle with fresh water and boil it once or twice
Discard the boiled water
Wipe the outside and inside with a clean cloth
Repeat if limescale remains