Can the glass be removed from water heater?

Yes, the glass can be removed from a water heater if it is designed to have a glass viewing window, commonly found in certain types of water heaters like those with a glass-lined tank. However, if you are referring to the glass lining within the tank itself, it is not meant to be removed as it is part of the tank's structure for insulation and protection. Always consult the manufacturer's guidelines or a professional before attempting any repairs or modifications.