Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hello Michael,
Thank you for explaining your situation. Since you no longer have access to the phone number registered for MFA, the first step is to recover administrative access to your Microsoft 365 tenant.
- Check for another sign-in method
At the MFA prompt, select Sign in another way, if available. You may be able to use another authentication method you previously registered.
- Check whether another Global Administrator can help
If another Global Administrator still has access, they may be able to reset your MFA registration through the Microsoft Entra admin center. The administrator must have the appropriate role, such as Global Administrator or Privileged Authentication Administrator.
Manage user authentication methods
- Contact Microsoft Support
If you are the only Global Administrator and cannot use another sign-in method, contact Microsoft through its customer support page.
Explain that you are locked out of a Microsoft 365 business tenant because your registered MFA phone number is no longer available. Ask the support representative to create a service request and route it to the Data Protection team for tenant access recovery.
Have any available proof of your former administrator role, organization details, and subscription or billing records ready for Microsoft's verification process. Please do not share these details publicly in this thread.
If you purchased the subscription through a reseller or Cloud Solution Provider (CSP), you can also contact them to check whether they can assist.
- Closing the organization
Once access is restored, you can cancel the subscription and proceed with deleting the Microsoft Entra tenant. These are separate steps, and the cancellation process depends on your billing agreement.
See Microsoft's guidance: Close your Microsoft business account.
Michael, were you the only Global Administrator, and did you purchase the subscription directly from Microsoft or through a reseller?
Kind regards,