Word stores the names of the last 10 people who worked on a document. This feature is hardwired into Word. You can’t turn it off. Luckily, there is a trick.
Save the document to another format, such as RTF, which does not capture this information.
Word deletes all information about the Author when it saves it to RTF or HTML.
In Word, reopen the RTF file and save it back to Word.