Delete child duplicate
How can you delete a duplicate child from family
iPhone XR, iOS 15
Some people have been able to delete extra accounts using the steps in the articles below.
Make sure that you sign out of all your devices to avoid issues with apps that use your Apple ID account or iCloud. After your account is deleted, you can't sign out of iCloud or turn off Find My iPhone Activation Lock on your devices. If you forget to sign out, you might not be able to use your device when your account is deleted.
How to delete your Apple ID account. *
What to do after you change your Apple ID or password - Apple Support -