public static void UnprotectDocument()
{
//Load the protected word file
WordFile wordFile = new WordFile();
WordDocument document = wordFile.Import(File.ReadAllBytes("Protected.docx"));
WordDocumentBuilder builder = new WordDocumentBuilder(document);
//If you have own the password, you can unprotect the document with password
//builder.Unprotect("password");
//If you don't own the password, you can unprotect the document without password
builder.Unprotect();
File.WriteAllBytes("Unprotected.docx", wordFile.Export(document));
}