hope this will help you..
function mymodule_views_pre_render(&$view) {
if ($view->name == 'view_name') {
// Here you can do any php you want to get the title you need for your view.
$view->build_info['title'] = "<h2>My custom title!</h2>";
}
or by views-view-unformatted--viewmachinename.tpl.php file
<?php if (!empty($title)): ?>
<h2><?php print $title; ?></h2>
<?php endif; ?>
<?php foreach ($rows as $id => $row): ?>
<div<?php if ($classes_array[$id]) { print ' class="' . $classes_array[$id] .'"'; } ?>>
<?php print $row; ?>
</div>
<?php endforeach; ?>