In fact, some banks will not even give you an effective means of removing such authorization. You may literally need a new bank account to keep your account from being emptied in the future.
You give the bank's routing number and your account number to the utility or whomever. That's all they need. That information, by the way, is present in clear text on every paper check you write. The bank doesn't pre-authorize anything, nor can they block anything short of closing your account and giving you a new account number. Your protection is that presenting a fradulent check (electronic or physical) is a crime.
You can reverse ACH transactions by going to your bank and filling about a form and making a declaration under penalty of perjury. It goes back to the merchant as an R10, and the merchant usually deals with it in some other form, though if they've got a good relationship with their bank, they can dishonor the return.