If you don't want or need a logo, open includes/templates/template_default/common/ tpl_header.php find and comment out this line of code by adding
“<!--” at the beginning,
“-->” at the end
and “//” between the words php and echo, as shown below.

<!-- <div id="logo">
<?php // echo '<a href="' . HTTP_SERVER . DIR_WS_CATALOG . '">' . zen_image($template->get_template_dir(HEADER_LOGO_IMAGE, DIR_WS_TEMPLATE, $current_page_base,'images'). '/' . HEADER_LOGO_IMAGE, HEADER_ALT_TEXT) . '</a>'; ?>
</div> -->

Save the file to includes/templates/CUSTOM/common/ tpl_header.php and upload it to your server.

(remember to do a backup ;) )