Your Equil Smartpen is not waterproof. Any exposure to water will damage it and nullify your warranty.
To remove ink stains, apply rubbing alcohol to a soft, dye-free fabric, such as cotton, then gently rub the affected area. Use a soft cloth for general cleaning, and keep food and any liquids away from your Equil Smartpen. Do not leave your Equil Smartpen in damp environments.