Hello,
This type of change would require custom programming changes. If you look in the index.php file for the Template you can see the menu call there such as:
<?php if ($s5_show_menu == "show" || $s5_pos_search == "published") { ?>
<div id="s5_menu_wrap">
<?php if ($s5_show_menu == "show") { ?>
<?php include("vertex/s5flex_menu/default.php"); ?>
<?php //include("vertex/responsive/responsive_mobile_menu.php"); ?>
<?php } ?>
<?php if($s5_pos_search == "published") { ?>
<div id="s5_search">
<?php s5_module_call('search','notitle'); ?>
</div>
<?php } ?>
<div style="clear:both; height:0px"></div>
</div>
<?php } ?>