Let me get the help you need to ensure you can cancel your QuickBooks Online (QBO) account.
To be sure we're on the same page, can you tell me more about the problem you encountered when cancelling your QBO account? Any extra information is much appreciated.
In the meantime, to cancel your account, follow these steps:
Sign in to QBO as an admin user.
Go to Settings ⚙ and select Account and Settings.
Select the Billing & Subscription tab.
In the QuickBooks section, select Cancel.
Follow the steps on the screen to cancel your subscription.