Let's get rid of the error message so you can cancel your trial subscription to QuickBooks Online (QBO).
There are times that the browser you're using had a data issue, thus causing QuickBooks to act weirdly. To verify, let's log in to your QBO account using a private browser. To do so, press this shortcut key on your keyboard:
Google Chrome: Ctrl + Shift + N
Mozilla Firefox: Ctrl + Shift + P
Safari: Command + Option + P
If this works, you need to clear the browser's cache so the system can start fresh. If you get the same result while using a private browser, I suggest switching to a different one.
Please know that once you've canceled your subscription during your 30-day free trial, you'll still be able to access QuickBooks until your next billing date. After that, you'll have read-only access to QuickBooks for one year starting from the date you cancel your subscription.