Hi SIrwin,
Change the domain that is used for your SharePoint Online website address, and then wait up to 24 hours. To change this domain, follow these steps:
- Sign in to the Office 365 portal (https://portal.microsoftonline.com) as a global administrator.
- In the header, click Admin, and then click Domains.
- On the Domains page, click Change Address next to Your SharePoint website address is http://www.[yourdomain.com].
- In the list, select [yourdomain].sharepoint.com, then click OK.
- Wait one hour, and then try to remove the domain. Check back periodically. The process could require up to 24 hours.
If the domain still cannot be removed, please refer to the following KB article and video to troubleshoot this issue:
You receive an error message when you try to remove a domain from Office 365
http://support.microsoft.com/kb/2284755
Thanks,
Jason Jiang