Hi @do vu
You can cancel your subscription by using the Cancel subscription button in your screenshot.
Cancel subscription in the Azure portal
https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/cancel-azure-subscription
Who can cancel a subscription?
If you are having troubles cancelling, please try creating an Azure Billing Ticket:
https://azure.microsoft.com/en-us/support/create-ticket/
---------------------------------------
If this is helpful please accept answer.