varwb=newXLWorkbook();varws=wb.Worksheets.Add("Protected No-Password");ws.Protect()// On this sheet we will only allow:.AllowElement(XLSheetProtectionElements.FormatCells)// Cell Formatting.AllowElement(XLSheetProtectionElements.InsertColumns)// Inserting Columns.AllowElement(XLSheetProtectionElements.DeleteColumns)// Deleting Columns.AllowElement(XLSheetProtectionElements.DeleteRows);// Deleting Rowsws.Cell("A1").SetFormulaA1("\"Locked, No Hidden (Default):\"").Style.Font.SetBold().Fill.SetBackgroundColor(XLColor.Cyan);ws.Cell("B1").Style.Border.SetOutsideBorder(XLBorderStyleValues.Medium);ws.Cell("A2").SetFormulaA1("\"Locked, Hidden:\"").Style.Font.SetBold().Fill.SetBackgroundColor(XLColor.Cyan);ws.Cell("B2").Style.Protection.SetHidden().Border.SetOutsideBorder(XLBorderStyleValues.Medium);ws.Cell("A3").SetFormulaA1("\"Not Locked, Hidden:\"").Style.Font.SetBold().Fill.SetBackgroundColor(XLColor.Cyan);ws.Cell("B3").Style.Protection.SetLocked(false).Protection.SetHidden().Border.SetOutsideBorder(XLBorderStyleValues.Medium);ws.Cell("A4").SetFormulaA1("\"Not Locked, Not Hidden:\"").Style.Font.SetBold().Fill.SetBackgroundColor(XLColor.Cyan);ws.Cell("B4").Style.Protection.SetLocked(false).Border.SetOutsideBorder(XLBorderStyleValues.Medium);ws.Columns().AdjustToContents();// Protect a sheet with a passwordvarprotectedSheet=wb.Worksheets.Add("Protected Password = 123");varprotection=protectedSheet.Protect("123");protection.AllowedElements=XLSheetProtectionElements.InsertRows|XLSheetProtectionElements.InsertColumns;wb.SaveAs("SheetProtection.xlsx");