Hi, @Iniobong Nkanga
Based on your description, I understand that you're experiencing an error when removing your domain.
It is typically due to one of the following reasons:
1.Default Domain: The domain might be set as the default domain for your Microsoft 365 subscription, and the default domain cannot be removed.
2.Associated Services: There may be services or users still associated with the domain. Ensure that no users, groups, or resources (like SharePoint sites) are using email addresses or aliases from this domain.
You need to first check that all the prerequisites for removing the domain are met.
More information can be found Remove a domain - Microsoft 365 admin | Microsoft Learn
To resolve this issue:
1.Check Dependencies: Make sure all dependencies are removed. Change the primary email address of users, groups, and resources that are still using the domain.
2.Change Default Domain: If it's the default domain, change the default domain to another one that you have.
For more information, see this thread Remove domain dependencies in Microsoft 365 - Microsoft Q&A
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