@Huy Nguyễn Greetings!
I understand your concern about being billed for the subscriptions even though the virtual machines were deleted. Just wanted to confirm if you cancelled your Azure subscription. If you have canceled your Azure subscription and removed your payment method, it is highly unlikely that you will be charged for any Azure services. After you cancel your final subscription, Azure closes your current billing cycle within 72 hours, or three calendar days. When the billing cycle ends, you receive your final invoice (bill) for the usage you incurred in the last billing cycle.
To get more clarity about the charges/your Azure billing, you could create an incident related to the billing - https://azure.microsoft.com/en-us/support/create-ticket/
Select Billing
in the Issue Type
field.
FYI: Billing support is free of charge:
Source : https://azure.microsoft.com/en-us/support/faq/#support-overview (How can I get support if I don't have a support plan?)
Hope this helps. Please let us know if you need any help further.
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