How can I remove a family member that is a child from my family

I added a family member(a 8 year old child) to compete the total 6 available members but I need to delete and reinstall them with a correct email address. When I go to delete the child it will not allow me to delete or remove. When I installed I used his email address but left off @gmail and it used @Icloud. He is not able to access the family but he shows as a family member.

Please help.