If the account was a Microsoft account, try the account recovery process. Go to account.live.com/acsr and follow the steps to recover the account.
You can also try to remove subscription using steps here: https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/cancel-azure-subscription
However, If you do not have access to the account you may need to reach out to Support. See:
Global Customer Service phone numbers
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Regards,
Abiola