If you feel that Sideline is not the best solution for you, you can absolutely cancel your service at any time.
Since all purchases are handled through the App Store, you will need to cancel it through your App Store account.
For steps on how to do this, please visit our help site article, "How to cancel and request a refund"
Please Note: Closing your account or uninstalling the app will not cancel your subscription.
If you have further questions, please submit a request.