I receive the delete action from market_by_price in EMA. I checked the map action with 
case MapEntry.MapAction.DELETE :
But when I tried to get the price to delete. The field 3427 (ORDER_PRC) is always empty. 
Below is the implementation
P.S. The code tag doesn't format the code nicely so I paste as plain text.
private void decodeMap(String ric, com.thomsonreuters.ema.access.Map map) {
  int  tmpSide = 0;
  double  tmpPrice = 0;
  double  tmpSize = 0;
  for (MapEntry mapEntry : map) {
  if (DataTypes.FIELD_LIST == mapEntry.loadType()) {
  FieldList fieldList = mapEntry.fieldList();
  for (FieldEntry fieldEntry : fieldList) {
  int fid = fieldEntry.fieldId();
  if (fieldEntry.code() == Data.DataCode.BLANK) {
  // noop
  }
  else {
  switch (fid) {
  case 3427: // ORDER PRICE
  tmpPrice = fieldEntry.real().asDouble(); 
  break;
  case 3428: // ORDER SIDE  
  tmpSide = fieldEntry.enumValue();
  break;
  case 3430: // NUMBER OF ORDERS, type: 4, OMMTypes.UINT = int
  tmpNumOrder = fieldEntry.uintValue();
  break;
  case 4356: // ACCUMULATED SIZE
  tmpSize = fieldEntry.real().asDouble();
  break;
  default: 
  break;
  }
  }
  }
  }
  if (mapEntry.action() == MapEntry.MapAction.DELETE && tmpPrice != 0d) { // orderbook delete operation
  // delete the entry in orderbook
  }
  }
  }