It’s pretty easy (depending on your CSS skills).
First look for this in your functions file –
//* Add support for 3-column footer widgets
add_theme_support( 'genesis-footer-widgets', 3 );
It may be set to 3 or 4. You can change it to 2.
Actually now that I think about it, you may not even have to do this step…..just use the first 2 widget areas if you want.
Next, you’ll need to change width of your Footer Widget 1 and 2. You’ll have to play around with the numbers, but you can start around 45 – 49%, and you can add some margin-left to the 2nd Footer Widget for space between the 2 widgets.
The responsive section should already be setup to take care of the width when the site is viewed on a mobile device.