Bruke nye Outlook på Windows for personlig e-post, kalender og kontaktbehandling
Unfortunately, if you accidentally deleted an email address (alias) from your Microsoft account while trying to change or replace it, and the email address ends in @hotmail.com, @outlook.com, @live.com, or @msn.com, it cannot be added back as an alias or used to create a new Microsoft account. It is permanently lost. I'm sorry.
Microsoft outlines this policy here: https://support.microsoft.com/office/add-or-remove-an-email-alias-in-outlook-com-459b1989-356d-40fa-a689-8f285b13f1f2