The European-based utility service ACN touts itself as a provider of telecommunications equipment and service. To that end, it provides residential users with services such as Broadband and dial-up Internet access, digital phone service and VoIP solutions. You subscribe to them in order to get their services by signing up for an account. If you want to cancel the account subscription, there's no online way to do it; you must call them directly.
Call ACN's customer service. A list of phone numbers is available on ACN's website. (See References.)
Inform the technician on the other end that you want to cancel your subscription. Confirm that you want to cancel when prompted. The tech will try to get you to stay on, so you may need to be firm about it.
Write down the confirmation number given to you by the technician.