I am unable to remove a member from Family Sharing

Read about how to remove anyone 13 or over if you are the Organizer. --> Leave Family Sharing - Apple Support

In some places the age may be older.

It would help if you could provide more information such as the exact wording of any messages you see.

Any family member age 13 or older can remove themselves from a family group. If you have Screen Time turned on for your account, the family organizer must remove you.

Learn how to ⇢ Leave Family Sharing - Apple Support

-Zachyy ✌️