Since you cannot delete a RosterGroup explicitly, you must break the connection or wait for a Roster change to receive a rosterModified() event, in order to be able to get rid of a deleted RosterGroup on the server. There’‘s no way of forcing a rosterModified event to do so. This causes an exception when a RosterGroup is deleted in a GUI and then a new one is created with the same name. Since setName() doesn’‘t work either, you can’‘t compensate for this by changing it’'s name to some arbitrary value to prevent the exception.