How do you change the number registered for iMessage? I want to delete the red one shown in the screenshot.
I can not seem to change it or tap it somehow. Can somebody help?
According to Apple, all you need to do is sign out of your device

 Source: https://appleid.apple.com/account/manageCheck your iCloud preferences after signing out and back in.Settings › iCloud › User Account › Contact Information

If you are unable to remove/modify

Depending on your carrier, you may need to remove your sim and reinstall iOS.