Before you begin, make sure you've noted which shared mailbox you need to remove the email address from.
- From the Microsoft 365 admin center, you can find the shared mailbox a couple of different ways:
From the admin center Home page, type the name of the shared mailbox into the search field, and then select it from the list. It will open the shared mailbox's details card.
Go to Groups > Shared mailboxes, and then select the shared mailbox from the list.
In the Name / Email and Aliases section, select Edit.
In the Email aliases section, remove the email address by clicking the remove (waste bin) icon, and then Save.
You can't remove the primary email address. If you need to remove the primary email address, add a second email address for this shared mailbox and click Set as primary. Then you can remove the email alias.