Hi David.
It takes few clicks to cancel a subscription purchased from the Apple App Store. I can guide you on how.
You can also use the official steps from Apple as your guide. Here's the link: How to cancel a subscription from Apple.
Moreover, here's how you can cancel your QuickBooks Online subscription or trial bought directly from Intuit and other stores.
For more hints and resources while working with QuickBooks, you can also open the topics from our help articles.
Please let me know how else I can assist you with your QuickBooks subscription. I'm always here to help. Have a good one!