How to unprotect Excel sheet if forgot the password

Personally I prefer the mentioned method with editing the text in the XML-file. It has never failed me and the same method works for both protected sheets, protected structure AND protected Word documents.
1: Tag name for a sheet is '<sheetProtection>' in (e.g.) 'Sheet1.xml'...
2: Tag name for protected sheet structure is '<workbookProtection>' in the file 'workbook.xml'...
3: Tag name for a protected Word document is '<w: documentProtection>' in the file 'settings.xml'...
To make the code editing even easier: Open the XML file in both(!) Notepad and a web browser. Then copy the code from the web browser and replace the code in the Notepad window. The tags in the Notepad window will be broken up into entire rows, like in the browser... and selecting/deleting the right text (not more/not less) will get easier. (Word wraps in the XML file when saving it doesn't matter.)