Remove word "on" from display

In the plugin .php code find this section of code (about a third of the way down the entire page):

if (!empty($pageList)) {
                echo "<ul>";
                    foreach ($pageList as $obj) {
                        echo "<li class='page_item page-item-{$obj->ID}'><a href='{$obj->uri}' title='{$obj->post_title}'>{$obj->post_title}</a>";
			if ($displayDate == 1) {
                            echo " on " . date($dateFormat, strtotime($obj->post_modified));
                        }
                        echo "</li>";
                    }
                echo "</ul>";
            }

And delete ” on ” . (from first ” to the full stop. This works for me.

Nope. It started to yell error and deleted the whole plugin!
When I put back the ” on ” it works fine again (and has the word ON there unfortunately..)