I'm using Adobe Acrobat X on a Mac.
I have made some edits to a PDF by adding text and lines. I want to save the file as a flat file so that no one can delete/edit my edits. In Windows, you can just print the PDF to PDF. When I try to do this on a Mac, it says "Saving a PDF file when printing is not supported. Instead, choose File > Save."
When I just choose File > Save, it just saves the PDF in the same format that allows those edits to be changed.
// Flatten all pages in the document
Once you've done that, restart Acrobat Pro and you'll find the "Flatten" option in your Edit menu. VERY handy! Tip: might want to save your original PDF file as a different version just to be safe---once you flatten the PDF, it can't be undone, so either just print and don't save, or save as different version if need be.