Simply paste the following code on the theme functions.php file. Specify the admin username on line 7 so the admin will still see the theme editor link.
function wpr_remove_editor_menu() {
remove_action('admin_menu', '_add_themes_utility_last', 101);
}
global $remove_submenu_page, $current_user;
get_currentuserinfo();
if($current_user->user_login == 'admin') { //Specify admin name here
add_action('admin_menu', 'wpr_remove_editor_menu', 1);
}