You can clean your scale using a lint-free cloth dampened with warm water.
Caution: The use of any detergents or cleaners may cause irreversible damage to the coating that protects the electrodes used to measure your body composition.
https://support.withings.com/hc/en-us/sections/10155347479953-Body-Comp
https://support.withings.com/hc/en-us/sections/8666358731281-Maintenance