Remove a domain from Office 365
Check the Domains FAQ if you don't find what you're looking for.
Are you removing your domain because you want to add it to a different Office 365 subscription plan? Or do you just want to cancel your subscription? You can change your plan or subscription or cancel your subscription.
Step 1: Move users to another domain
Choose Users > Active Users.
Select the boxes next to the names of the users who you want to move.
In the Bulk actions pane, choose Edit domains.
In the Edit domains pane, choose a different domain.
Choose Set as primary, then choose Save.
You'll need to do this for yourself, too, if you're on the domain that you want to remove. When you edit the domain for your account, you'll have to log out and log back in using the new domain you chose to continue.
For example, if you're logged in as *firstname.lastname@example.org* :
Go to Users > Active Users, select your account from the list, and then choose Edit in the Username row in the left pane.
Choosea different domain: contoso.com
Choose Set as primary, choose Save, and then Close.
At the top, choose your account name, then choose Sign Out.
Sign in with the new domain and your same password: *email@example.com*
Step 2: Move groups to another domain
Choose Groups > Groups.
Select the box for any group or distribution listassociated with the domain that you want to remove.
In the right pane, next to the group name, choose Edit.
Under Group Id, use the drop-down to choose another domain.
Choose Save, then Close. Repeat this process for any groups or distribution lists associated with the domain that you want to remove.
Step 3: Remove the old domain
Choose Setup > Domains.
On the Domains page, choose the domain that you want to remove.
In the right pane, choose Remove.
Follow any additional prompts, and then choose Close.
How long does it take for a domain to be removed?
It can as little as 5 minutes for Office 365 to remove a domain if it's not referenced in a lot of places such as security groups, distribution lists, users, and Office 365 groups. If there are many references that use the domain it can take several hours (a day) for the domain to be removed.
If you have hundreds or thousands of users, use PowerShell to query for all users and then move them to another domain. Otherwise, it's possible for a handful of users to be missed in the UI, and then when you go to remove the domain, you won't be able to and you won't know why. See Set-MsolUserPrincipalName for more information. To set the default domain, use Set-MsolDomain.