Open up wp-content/themes/gradient-child-theme-10/lib/php/tr_base.php. Find the following big of code and change the bit in bold
// Enable Custom Logo
function gradient_logo() {
global $tr_gradient_logo_visible, $tr_gradient_logo_url; ?>
<div id="gradient_branding" class="clearfix">
<h2 id="logo">
<a href="<?php bloginfo('wpurl'); ?>">
<?php if($tr_gradient_logo_visible === 'true') { ?>
<img src="<?php echo $tr_gradient_logo_url; ?>" alt="<?php bloginfo('name'); ?>" title="<?php bloginfo('name'); ?>"/>
<?php } else { ?><span id="logo_text"><?php bloginfo('name'); } ?>
</a>
</h2>
</div>
<?php }
to
<a href="/">