Make a copy of the original document and rename it to have the .zip extension.
Extract .zip file and in the contents find word\settings.xml
Edit settings.xml to remove the XML element beginning with w:documentprotection. Remove everything including < and >
Copy the word directory to the same location as your document.zip file.
Rename your file to word.zip
Right click word directory and choose 7zip → Add to “word.zip”
Rename word.zip to yourformname.docx
Do a little dance and be happy that this episode of your life is now over.