Delete child account

Hello Btttyy,

This page you may have viewed will have some helpful info near the bottom regarding the deletion of a child's Apple ID in a Family Sharing group: Move a child to another group using Family Sharing - Apple Support

Delete the child's account

Children under 13* can't be removed from a family group. Instead, you or another guardian can delete their account, and if needed, create a new account for your child. 

* Age varies by country or region.

This will then link to the main page regarding deleting an Apple ID here: How to delete your Apple ID account - Apple Support

On there it'll help to note the following on the topic:

Can I delete my child’s account?

If you are the organizer of your family, you can delete your child’s Apple ID when you request deletion of your account. Your child can also request deletion of their Apple ID, which requires your approval.

The approval request will be sent via email to the primary Apple ID email address of your family organizer account. When approving the request from this email, you will go through the process of deleting the child account.

Cheers.