How can I decrypt protected structure and windows in excel file?
Manually we can remove from Review -> Protect Workbook -> Protect Structure and Windows.
Also, I found another interesting thing. If we set the password for the whole workbook (Save as -> Tools -> General Options) and decrypt the file using OfficeCrypto, the sheet is readable although we set Protected Structure and Windows before save.
But, if we don't set the password at workbook level like former, we cannot use OfficeCrypto.DecryptToStream because the file is no longer password protected workbook (only workbook structure is protected).