Which task can a Group Admin who is not a System Admin perform?

The task that a Group Admin who is not a System Admin can perform is removing a user from a group they own. Group Admins have specific permissions that allow them to manage the membership of the groups they oversee. This includes the ability to add or remove users as necessary to maintain the group's functionality and purpose.

In contrast, other options relate to permissions typically reserved for System Admins or require ownership beyond what a Group Admin possesses. Assigning the Group Admin role to another user involves higher-level permissions since it affects the administrative structure of the group. Changing settings to allow external users to join a group often requires System Admin privileges, which ensures that the overall security and governance policies are upheld. Deleting a group that they do not own also falls outside the responsibilities of a Group Admin, as any deletion action typically requires ownership or elevated privileges to prevent unauthorized changes to any group structure.