Hi,
Do you currently have access to your account?
If yes, please make sure you are signed in to your account.
Click this link: https://account.live.com/proofs/Manage
Click “Add a new way to sign in or verify.”
Choose “Email a code” or “Text a code.”
Enter your new email address or phone number as your recovery method.
You will receive a code through the selected method.
Enter the code in the field provided, then click Next.
Follow the prompts to complete the process.
Once the new method is added, you can safely remove the old phone number from your account.