Canceling your subscription is as simple as disabling backup for all your companies.
Go to the Companies page and click the gear icon to disable backup.
Once you've disabled backup for all your companies, you will receive an email confirming your subscription cancelation.
Please note that an active subscription is required to maintain your backups that can be restored to QuickBooks Online. Alternatively, you can use a ChronoBooks Local Backup if you won't need to get it back into QuickBooks Online.