Hello Alex Oliveira de Souza,
Thank you for posting your query on Microsoft Q&A.
As per the description, we understand that when you are signing into Azure Portal to manage your API, you are not able to complete MFA as you don't have Authenticator App installed on your phone.
I have provided the steps below to reset and unblock MFA in Azure Active Directory via Azure Portal and PowerShell.
Using Azure Portal:
Sign in to the Azure portal with the tenant Global Administrator account.
Navigate to Azure Active Directory > Users > All users > Choose the user you wish to perform an action on > select Authentication methods > Require Re-register MFA.
Once this is done, the next time the user signs in, he/she will be requested to set up a new MFA authentication method.
Note: The user's currently registered authentication methods aren't deleted when an admin requires re-registration for MFA. After a user re-registers for MFA, we recommend they review their security info and delete any previously registered authentication methods that are no longer usable.
Using PowerShell :
Install the MSOnline PowerShell module.
- Run Connect-MSOLService and sign in with the Global Administrator account.
- Run ***Set-MsolUser -UserPrincipalName ***@contoso.com -StrongAuthenticationMethods @() cmdlet to reset the MFA registration information.
Please refer the below document.
https://learn.microsoft.com/en-us/entra/identity/authentication/howto-mfa-userdevicesettings
I hope this information is helpful. Please feel free to reach out if you have any further questions.
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