Apr 06 2020 04:31 AM
Apr 06 2020 05:24 AM
here is the details document that explains about OnMicrosoft cases you can and you cannot do.
You can't rename the onmicrosoft domain after sign-up. For example, if the initial domain you chose was fourthcoffee.onmicrosoft.com, you can't change it to be fabrikam.onmicrosoft.com. To use a different onmicrosoft.com domain, you'd have to start a new subscription with Office 365.
You can't rename your team site URL. Your team site URL is based on your onmicrosoft.com domain name. Unfortunately, because of the way SharePoint Online architecture works, you can't rename the team site.
You can't remove your onmicrosoft domain.Office 365 needs to keep it around because it's used behind the scenes for your subscription. But you don't have to use the domain yourself after you've added a custom domain.
You can keep using the initial onmicrosoft.com domain even after you add your domain. It still works for email and other services, so it's your choice.
Apr 06 2020 05:35 AM
Microsoft 365 needs to keep it around because it's used behind the scenes for your subscription.
But you don't have to use the domain yourself after you've added a custom domain and the reason it is there since while you were doing subscription to Microsoft 365 that was selected by default so if you want to create a new Tenant you can create it without this but you cannot remove it from existing one.
Apr 06 2020 08:30 AM
@AllinillaOhh no problem at all this is why we are part of this great Microsoft Tech Community,
I think it is more of your own setting you should be able to remove it from every user if you already have a custom domain which I believe you do, so if you have Hybrid Exchange you can do it from On-prem if you have only Exchange online do it there.
i hope this will give you the answer you are looking for!