How can I cancel my subscription?

You can cancel your Dialed subscription at any time! All in-app purchases are handled by the App Store, so you can cancel your subscription through your iTunes account. 

Here is the support article from Apple, it's essentially the same but they include screenshots: https://support.apple.com/en-us/HT202039

If you purchased a Dialed subscription from one of our third party providers, you will need to contact their support to get cancelation instructions. You cannot cancel a third party subscription from within the Dialed app or via our support team.