Protect Excel Files in C#

protect-excel-files.cs

// Open the Excel file
Workbook workbook = new Workbook("Excel.xlsx");

// Protect workbook by specifying protection type
workbook.Protect(ProtectionType.All, "12345");

// Save the file
workbook.Save("Excel.xlsx");

unprotect-excel-files.cs

// Open the Excel file
Workbook workbook = new Workbook("Excel.xlsx");

// Unprotect workbook
workbook.Unprotect("12345");

// Set password to null
workbook.Settings.Password = null;

// Save the file
workbook.Save("Excel.xlsx");