public void RemoveSheetAt(int index) { // Get the sheet to be removed var xSheet = (XSSFSheet)XssfWorkbook.GetSheetAt(index); var sxSheet = GetSXSSFSheet(xSheet); // De-register it XssfWorkbook.RemoveSheetAt(index); DeregisterSheetMapping(xSheet); // Clean up temporary resources try { sxSheet.Dispose(); } catch (IOException e) { logger.Log(POILogger.WARN, e); } }