Your data will be available in read-only access for a year once you cancel your subscription. I'd recommend exporting or printing your data before doing so. This ensures you'll have a handy copy of your file.
If you're ready to cancel your account, I'd suggest following the steps below:
In case you'd like to reactivate your account in the future, please follow the instructions on this article to do so: Resubscribe QuickBooks Online.
Feel free to comment down below if you have any other concerns or questions about canceling your QuickBooks account. I'm always glad to help in any way I can.