Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Dear Killy Yin,
Please note that since your account is belonged to an organization (your university/ school), none of moderators could help you do this action. Kindly follow these steps:
Please contact your IT Admin to revoke your MFA. Manage authentication methods for Microsoft Entra multifactor authentication - Microsoft Entra ID | Microsoft Learn
In case you do not know who your IT Admin is, please refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support
If they still could not do it, please ask them to raising a support. A technical support engineer can perform a remote session to investigate the situation verify the backend configurations, and run any necessary synchronization tools to resolve the problem.
The IT Admin should create a service request with Microsoft support to get advanced technical assistance and diagnostics. For detailed instructions on how to get support, please refer to Get support - Microsoft 365 admin.
I hope the information shared helps point you in the right direction.