I can show you what you have to do to cancel your subscription and how to go about a refund request, @luis-altuna.
The process of refund will depend on when and where you purchase your subscription. If you purchased an annual subscription for QuickBooks Online, and it’s within 60 days of the purchase date, you’re eligible for a refund under our satisfaction guarantee. There are some exceptions, so check our return policy for details. For more details, click this article: Request a refund for your QuickBooks product
Also, I'd suggest contacting our Customer Support Team. They can check your account securely and process the refund for you. Just follow the steps on this article on how to contact the QuickBooks Online Customer Support team.
In case you want to cancel your QuickBooks Online subscription so that you will not be billed for the subscription fee. I'll be glad to walk you through the steps in doing it.
Here's how:
Click the Gear ⚙ icon.
Choose Account and Settings.
Select the Billing & Subscription tab.
In the QuickBooks section, select Cancel.
Follow the steps on the screen to cancel your subscription.
For billed subscriptions, you can still view the records of the canceled account for a year. You can read this article for more information: Cancel your QuickBooks Online subscription.