code: public void removeExtendedRow(final int idx) {
          DynaFormRow rowToBeRemoved = null;
          if (0 <= idx && idx < extendedRows.size()) {
              rowToBeRemoved = extendedRows.get(idx);
          }
  
          if (rowToBeRemoved != null) {
              removeRow(extendedRows, rowToBeRemoved, idx);
          }
      }
docs: Removes the extended row by its index (position in the list).
  
  @param idx index of the row to be removed