If you use highlighter marks in Word to indicate sections that need work or for some other purpose, you may feel obliged to wipe them all out before printing the document. But there's no need to go to all of that trouble - unless you're really done with them or want to share the file without them being visible.
In Word 2010, just go to File, Options and then visit the Display tab (in Word 2007, access Options via the Office button). Now simply uncheck the box next to Show highlighter marks:
All marks (even new ones!) will be invisible on your screen and when you print until you toggle this setting back on.
Just be aware that if you share the file, others will still see the highlighter marks unless they too have switched this setting off.