Usually I wouldn’t recommend bypassing security, but less so when I have suggested workflow updates to a template whose maintainer had left.

Firstly, if the Office/Excel file has been encrypted to prevent opening without a password, this will not help. From what I have seen with the new Office formats, this is even harder to bypass, and often requires paid tools to even attempt.

These are quick hack instructions from many other websites, with my own inclusions.

• Confirm you can see file extensions (view menu in Explorer).
• Change the file extension from .XLSX to .ZIP
• Extract the file to a folder with your favorite unzipper like 7zip, or open with Explorer.
• Go to the xl and then worksheets sub-folders.
• There are files named like: sheet1.xml (sheet2.xml, etc). Inside of one of those files is an XML tag: <sheetProtection password=… />. Delete that entire XML tag. I also found this in the workbook.xml file.
• Re-zip or insert the files back.
• Rename from .ZIP to .XLSX
• Test and confirm before handing back. The “Unhide” tabs option is available by right clicking an existing tab. Get the team to keep a secure password repository to put the new Protection password.

I hope this helps someone as it did me.