Remove a user from a user group.
The user must be authorised to administer the user group.
The user group and the user can be identified by either identifiers or references.
If the member user identifier is invalid, or not a member of the group, no error is raised. (i.e. if you try removing from a group someone who is not in the group, this is not a problem).
101 - Not authorised
102 - Not found
103 - Parameter error
105 - User error