If you're hosting the files yourself, you should have installed a file called "timeline.css". You'll want to make the changes in there. Adding these lines at the end of that file should hide the navigation.
If you're just embedding the timeline, try adding these changes to a stylesheet for the page...
.vco-timeline .vco-navigation { display:none !important; }
.vco-storyjs .vco-feature .slider, .vco-storyjs .vco-feature .vco-slider { box-shadow: none !important; }
In both cases it won't expand the main content area down to fill the space normally taken up by the nav, it will just hide it.