The border may be a graphic (designed to look like a border) which is anchored to the page header and therefore repeated on multiple pages. Double-click the header to find out. If you want to upload a screen shot for illustration, that might help us diagnose the issue.
Page Borders in Word - Why does my Word document suddenly have a page border and why can't I remove it the normal way?
I've been working on a long manuscript for years. Suddenly every page has a border. When I go to Page Borders and choose None, the borders remain. I've watched many tutorial videos, and read many Q&A's and they all offer the same solution that doesn't work for me. Any suggestions?