Do you need your own motorcycle to get the license or will they provide you with one if not then can you drive off after buying it without a license from the dealer?

You do not have to own a motorcycle in order to get a motorcycle license. Some states do have motorcycle training programs where they will provide a motorcycle for you to learn on and get a license. Most states have a learners permit where you can ride while you are learning. You would be able to drive a motorcycle from a dealership if you had a permit.