how to get rid of "#EXT#@" after personal email account

Hi Stéphane,

Thank you for sharing the details of your situation.

As this is a user-to-user support forum, I do not have access to the former university’s tenant and cannot remove the guest account directly. I can only provide guidance and point you in the right direction if further assistance is needed.

To remove the association, you can try the steps below:

1. Open https://myaccount.microsoft.com/organizations in a private or incognito browser window.
2. Sign in using the personal Gmail account that was originally invited by Lincoln University.
3. Locate the former university under Other organizations you collaborate with.
4. Select Leave organization and follow the prompts.

Leaving the organization will remove your access to its applications and resources.

If the Leave organization option is unavailable or you cannot access the account, you will need to contact the former university's IT department and ask them to delete the guest account associated with your Gmail address from their Microsoft Entra tenant. The guest account is managed by Lincoln University, so your new university cannot remove it on your behalf.

After the guest account has been removed, sign out of all Microsoft and Azure sessions, clear your browser cookies and cache, and then try signing in to Azure again using a private browser window.

• In case you do not know who is your IT admin, kindly refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support  

I hope this information helps move the case forward. Should you have any further questions or need additional assistance, please feel free to share them in the comment below. I'm very happy to help.  

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