How to remove my phone number from a stolen iPhone's Apple Account?

Remove the device from your Apple Account

To remove a device from your Apple Account:

1. Go to account.apple.com.
2. From the sidebar, choose Devices.
3. Select your device, scroll down, then select Remove from account.

If you filed a claim with AppleCare+ with Theft and Loss, don't remove the device from your Apple Account (or from Find My) until your claim has been fully approved.

Review and update your Apple Account information

1. Go to account.apple.com. If you can't sign in, try to reset your password.
2. From the sidebar, choose Sign-In and Security.
3. Review the email and phone numbers associated with your account, the trusted phone numbers and devices listed under Account Security, your Account Recovery Methods, and make sure that your password hasn't been changed.
4. Update any information that you don't recognize and remove any email address, phone numbers, or trusted devices or numbers that you don't recognize or didn't add.

If this is not working, you might want to contact your carrier and get your old number blocked

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