Remove Admin Name in Recent Comment Sidebar Using Exec PHP

<?php
global $wpdb;
$sql = "SELECT DISTINCT ID, post_title, post_password, comment_ID,
comment_post_ID, comment_author, comment_date_gmt, comment_approved,
comment_type,comment_author_url, comment_author_email
FROM $wpdb->comments
LEFT OUTER JOIN $wpdb->posts ON ($wpdb->comments.comment_post_ID =
$wpdb->posts.ID)
WHERE comment_approved = '1' AND comment_author_email != 'YOUR-ADMIN-EMAIL' AND comment_type = '' AND
post_password = ''
ORDER BY comment_date_gmt DESC
LIMIT 5";
$comments = $wpdb->get_results($sql);
$output = $pre_HTML;
$output .= "\n<ul>";
foreach ($comments as $comment) {
$output .= "\n<li><a rel=\"nofollow\" href=\"" .strip_tags($comment->comment_author_url)
. "\" >" .strip_tags($comment->comment_author)
."</a> on " . "<a href=\"" . get_permalink($comment->ID) .
"#comment-" . $comment->comment_ID . "\" >" .
$comment->post_title ."</a></li>";
}
$output .= "\n</ul>";
$output .= $post_HTML;
echo $output;?>