Both workbook protection and sheet protection can be removed from an Excel workbook file without the protection password in four basic steps:
- Unzip the .xlsx or .xlsm file so that its contents may be modified in the following steps. Excel workbook files are actually ZIP files with a different file name extension.
- Remove the <workbookProtection ... /> XML tag from the xl\workbook.xml file.
- Remove the <sheetProtection ... /> XML tag from any .xml file in the xl\worksheets\ directory.
- Zip the modified Excel workbook file contents, using the .xlsx or .xlsm filename extension for the resulting ZIP file.
Yes. Excel workbook files are governed by the ECMA-376 standard, which clearly states that workbook protection and sheet protection are not intended to provide file security.
To read this in the original, see Section 18.2.29 of ECMA-376-1:2016, which can be found at the link titled "ECMA-376 5th edition Part 1" on the official
Removing Excel Protection
is a PDF guide (with screenshots!) for removing both workbook protection and
sheet protection from an Excel workbook file using only built in Windows utilities (File Explorer & Notepad).