Reduce white space in a template

Our website is up and live, and it’s a pre-purchased template which has been modified. As my webdev is away for a few weeks (and she knows I want to do it), I’d like to be able to withdraw some of the white space under the slider graphic and the next section.

The creator needs you to register the purchase code to do anything on his forum (webev has it) so I’m turning to you ! Is there something in the CSS file I can modify ?