Managing personal Outlook.com account settings, security, and privacy
Hi,
This happens due to unusual activity that triggers the security system to verify using your verification method. May I ask if you are currently able to sign in to your account? If so, please go to the link below.
https://account.live.com/proofs/manage/additional
Then, add another way to sign in to your account or remove your old email verification by expanding the email code and clicking Remove. If it asks for verification using the old email address to remove it, I suggest adding another way to sign in to your account and disabling received alerts. I suggest waiting at least a day and trying to remove the old email address.
Please let me know how it goes. I look forward to your response.
Stay Safe!