code: public function removeCellStyleXfByIndex($pIndex)
      {
          if ($pIndex > count($this->cellStyleXfCollection) - 1) {
              throw new Exception('CellStyleXf index is out of bounds.');
          }
          array_splice($this->cellStyleXfCollection, $pIndex, 1);
      }
docs: Remove cellStyleXf by index.
  
  @param int $pIndex Index to cellXf
  
  @throws Exception