It's the first time I see those bar and can't figure out a way to remove them. My search on the web lead nowhere, I can't right click on it, it's only visible in the print layout view.
See image here:
It sounds like they are object of some kind which are part of the document content. Try turning on formatting marks and see if it is a shape or has an anchor. Otherwise try removing parts of your document one by one until it disappears. You can then narrow down where these objects are located.