Workshare Protect is described as 'leading document protection tool. Our document protection software also allows you to remove hidden metadata from excel, PowerPoint and PDFs'. There are four alternatives to Workshare Protect for a variety of platforms, including Windows, Linux, Mac, Microsoft Office 365 and Microsoft Office Outlook. The best alternative is GroupDocs.Metadata for .NET. It's not free, so if you're looking for a free alternative, you could try mat2. Other great apps like Workshare Protect are cleanDocs (Paid) and Batch Edit Office Properties (Paid).
cleanDocs is a metadata removal tool. It protects organizations from accidental information and metadata leaks. cleanDocs integrates tightly with email systems to ensure all hidden metadata is removed from documents sent outside of an organization.
mat2 is a metadata removal tool, supporting a wide range of commonly used file formats, written in python3: at its core, it's a library, used by an eponymous command-line interface, as well as several file manager extensions.