To cancel, you will need to call 866-347-3292. You may have to pay an early termination fee if you're still under contract. See https://legal.hughesnet.com/ForYourHome.cfm
To avoid equipment charges, you will also need to return the equipment (modem, power pack, and the radio from the dish). You will get a kit to return the equipment when you cancel the account. The instructions for removing the radio will be included in the return kit.