Tool: iPhone 12.
Operating system: iOS 14.4. 1.
Set 2.0.
1. First unlock iPhone 1 1, and click the icon set in the system version: iOS 13.6.
2. Then in the setting interface, click the AppleID above to enter.
3. After input, select the password and security options.
4. After clicking, under double authentication, click Edit in the upper right corner of the mobile phone number.
5. After that, select the option to add a trusted phone number below.
6. After clicking, enter the available mobile phone number and click Send in the upper right corner.
7. After the verification is successful, click the edit option on the upper right again.
8. Click on the unused mobile phone number and select the delete option at the back.
9. Finally, select the Remove option in the pop-up prompt, and the unused number will be removed and replaced successfully.