Shaving a double-coated cat is a big no-no (unless it is for veterinary reasons, such as removing the coat to prepare for a surgical procedure).
If you remove your cat's coat, your cat won't be able to keep themselves warm as they use their coats to regulate their body temperature, if they get wet their body temperature will decrease very quickly. If shaved, they will be without protection from the sun. A cat's coat also helps conceal them from prey and predators.