Remove someone from family sharing

As the organizer, you can remove anybody in the group. Use the following article: https://support.apple.com/guide/iphone/add-or-remove-family-sharing-members-iph8f958ab3f/ios. The section that will mostly likely apply is, "Go to Settings > [your name] > Family Sharing. Tap [member's name], then tap Remove[member's name] from Family."

If you're just a member, you don't.

See this support article:--> Leave Family Sharing - Apple Support

Regards

Giulio