Since your site is using a grid system, in order to make a full-width template, you’ll need to have FTP access (you will need to copy all the code from page.php and create a new file called full-width.php).
At the top of full-width.php, add this code:
/*
Template Name: Full Width
*/
After you add that code (which specifies that it’s a Template page), you should see code that looks like this:
<div class="content-container">
<div class="container_24">
<div class="grid_24">
<div class="content-main">
<div class="grid_16 alpha">
<div class="grid_8 omega">
</div>
</div>
<div class="clear"></div>
</div>
</div>
To get the content area to expand to the full width of the site, you’ll need to change:
<div class="grid_16 alpha">
to
<div class="grid_24">
and then remove the:
<div class="grid_8 omega">
Removing <div class="grid_8 omega">
will get rid of the sidebar.