Worksheet.Unprotect Method (Object)
Removes protection from the worksheet. This method has no effect if the worksheet is not protected.
Assembly: Microsoft.Office.Tools.Excel (in Microsoft.Office.Tools.Excel.dll)
The case-sensitive password to use to unprotect the worksheet. If the worksheet is not protected with a password, this argument is ignored. If you omit this argument for a worksheet that is protected with a password, you will be prompted for the password.