Remove Guest Organisation from User where you no longer have the permission to login

Hi ShiGGi2408,

although your coworker doesn’t have access, they can still try to leave the organization manually (if the suggestion from Paul_Keijzers doesn't work).

He can try to do this following these steps:

1. Go to https://myapps.microsoft.com
2. Click on the Name icon on Top-right, then click on the 3 dots and click on Leave new experience.
3. On the reloaded to page, click on the Picture or icon and then click the Cog.
4. Click on Leave Organization next to the one that's listed as Guest in Teams.

Be aware that a guest user can’t leave an organization if their account is disabled in either the home tenant or the resource tenant.

If their account is disabled, the guest user will need to contact the tenant admin, who can either delete the guest account or enable the guest account so the user can leave the organization.

Wish To Remove guest account from MS teams desktop App - Microsoft Community Hub

Leave an organization as a guest user - Microsoft Entra External ID | Microsoft Learn