[DerekM]

It's in the header settings. File > Print > Change the drop down menu that is probably set to "OmniOutliner" to "Headers & Footers". Now the part that could probably use some UI tweak to– the header and footer are both appearing empty, this is because you're looking at the "Master Page". Change that menu to "First Page" and you'll see the document name is set there. Delete that and it will no longer be in the printout.