private Monitor removeMon(String label,String detail,String units){
  MonKey key=getMonKey(label,detail,units);
  Monitor mon=(Monitor)map.get(key);
  if (mon != null)   map.remove(mon);
  return mon;
}

private Monitor removeMon ( String label , String detail , String units ) { MonKey key = getMonKey ( label , detail , units ) ; Monitor mon = ( Monitor ) map . get ( key ) ; if ( mon != null ) map . remove ( mon ) ; return mon ; }
remove monitor from map and also return it . this is done in conjunction with calls to stop and skip .
