We hate that you're planning to leave, but rest assured I'm going to help you sort this out. If you purchased directly on the QuickBooks website, you should be able to see the Cancel subscription under the Billing & Subscription tab.
You may have experienced a cache-related issue as a result of having too much data cached on your browser. Let's perform some troubleshooting steps to fix it. Begin by signing into your account using an incognito window and making sure you're logged in as master admin. The shortcut keys are as follows:
Google Chrome: Ctrl + Shift + N
Mozilla Firefox: Ctrl + Shift + P
Safari: Command + Shift + N
Return to your regular browser and clear the cache if you can access the Billing & Subscription page. This will let you remove your browsing history and start to refresh the program. If that doesn't work, try one of the other supported browsers.