There are two possible reasons why the Cancel subscription button is missing from your account. First is the user access. When trying to cancel an account, make sure to log in as a company admin or an accountant. If you open QuickBooks as an admin or accountant and the button is still missing, you can proceed to the second troubleshooting steps to isolate the error.
To do this, access QuickBooks via a private browser to check if it's a browser issue or not.
To save you time, use either of these keyboard shortcuts:
Google Chrome: Ctrl + Shift + N
Mozilla Firefox: Ctrl + Shift + P
Safari: Command + Shift + N
Then, check if the button is now available from your account.
Go to the Gear icon, then select Account and Settings under Your Company.
Click on Billing & Subscription at the left pane.
Look for your subscription, then click on Cancel subscription for a paid subscription and Cancel your trial for a trial account.