Go to this TurboTax support FAQ for information on cancelling an Advantage subscription - https://ttlc.intuit.com/questions/1901052-how-do-i-cancel-my-turbotax-advantage-subscription
I agree you should shop for the best price but make sure you are getting the same product ... the Deluxe version is sold WITH & WITHOUT the state program when you do not buy directly from Turbotax.