header şablonundan bunu bulun ve silin.
Kod:
<form action="{$mybb->settings['bburl']}/search.php" method="post"><fieldset class="noborder"><label for="search_box"></label><input name="keywords" id="search_box" title="Enter your search keywords" type="text" /><input type="image" src="images/fortress/search.png" alt="search" name="submit-search" id="search_button" type="submit" /><input type="hidden" name="action" value="do_search" /></fieldset></form>