Can you cancel an auto lease contract?

It depends on where you are. In some U.S. states, state law allows a purchaser a few days or a week to change his or her mind. This is generally called a "cooling off period."

In others (TN is one of these), the moment you sign the contract, you are obligated and the only way to get out of the contract is to get the dealer to agree to cancel it, which is very unlikely.