Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hello Soulfood Spices,
Hope you are doing well. Thank you for reaching out to the Microsoft community.
I would like to know whether your tenant have more than one Global admin. If so, please ask another admin to unregister the old device/disable the MFA setting.
Supporting document for MFA: Setting up multi-factor authentication for users - Microsoft 365 admin | Microsoft Learn
If you are the admin only and can’t access your account due to Authentication issue, it is suggested to contact Data Protection team, because we are from community team and we are not authorized to reset any user/admin account. Data Protection Team is the only support team to check and reset account. To find contact number of Data Protection team, please check Find Microsoft 365 for business support phone numbers by country or region - Microsoft 365 admin | Microsoft Learn or Global Customer Service phone numbers - Microsoft Support.
If any information is required, kindly let us know. Thank you in advance for your understanding. Your patience and cooperation will be greatly appreciated. I hope for all the best!
Sincerely
Nafis Iqbal Shuvo