Hello Dave,
I am a Microsoft user like you, providing solutions to community members; I am NOT a Microsoft employee.
I am sorry to hear that you're unable to remove a guest user from a SharePoint group despite having the "Member" role Dave. Here are a few potential solutions to this issue:
Check Your Permissions:
Site Owner Role: Verify if you have the "Site Owner" role. Only site owners can typically remove members from a group.
Group Membership: Check if the guest user is part of a specific group within the SharePoint site. If so, you might need to remove them from that group first.
Advanced Permission Settings:
Access the advanced permission settings for the site.
Navigate to the group where the guest user is a member.
Remove the guest user from the group directly.
SharePoint Admin Involvement:
If you're unable to resolve the issue, contact your SharePoint administrator. They might have additional tools or permissions to remove the guest user.
Guest Expiration:
If the guest user's access is temporary, wait for their guest access to expire automatically.
Additionally, sometimes, clearing your browser cache can resolve display issues. Also test if the issue persists on a different browser.
Hope this helps
-Stephen N.