If the new email says it is already in use, that address is already associated with another Microsoft account and cannot be added as an alias to this account. Existing @hotmail.com, @live.com, @outlook.com, and @msn.com addresses also cannot be added as aliases to another Microsoft account.
If the current alias cannot be removed, it is usually because it is still the primary alias. A Microsoft account must keep a primary alias until another alias is added and set as primary.
Try this exact path:
- Sign in to Your info on the Microsoft account site.
- Open Manage how you sign in to Microsoft.
- Select Add email.
- Add either:
- a non-Microsoft email address that is not already tied to another Microsoft account, or
- a new Outlook.com email address.
- Complete the verification steps.
- After the new alias appears in the Account aliases list, select Make primary next to it.
- Then select Remove next to the old alias.
Important limits from Microsoft:
- An alias cannot already belong to another Microsoft account.
- Aliases cannot be used to share information between two Microsoft accounts.
- If the only alias on the account is the current one, it cannot be removed until another alias is added and made primary.
If the problem is the “Which account do you want to use?” prompt because the same email exists as both a personal account and a work or school account, Microsoft’s supported fix is to rename the personal Microsoft account by adding another alias and making it primary.
If support chat has already not resolved it, use the account recovery/support path from the Microsoft account page:
- Edit account info: https://account.live.com/names/manage
- Guided support tool: https://go.microsoft.com/fwlink/?linkid=2216784
- Sign-in helper: https://go.microsoft.com/fwlink/?linkid=2300860
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