add in cp.php where members are deleted.

below this

$db->query("DELETE FROM ".X_PREFIX."members WHERE uid=$delete");

					$qf = $db->query("SELECT fid, lastpost FROM ".X_PREFIX."forums WHERE lastpost LIKE '%|$dbname|%'");
					while($result = $db->fetch_array($qf)) {
						$newlastpost = str_replace("|$dbname|", "|Anonymous|", $db->escape_var($result['lastpost']));
						$db->query("UPDATE ".X_PREFIX."forums SET lastpost='$newlastpost' WHERE fid={$result['fid']}");
					}
					$db->free_result($qf);

					$qt = $db->query("SELECT tid, lastpost FROM ".X_PREFIX."threads WHERE lastpost LIKE '%|$dbname|%'");
					while($result = $db->fetch_array($qt)) {
						$newlastpost = str_replace("|$dbname|", "|Anonymous|", $db->escape_var($result['lastpost']));
						$db->query("UPDATE ".X_PREFIX."threads SET lastpost='$newlastpost' WHERE tid={$result['tid']}");
					}
					$db->free_result($qt);
					
					$db->query("UPDATE ".X_PREFIX."posts SET author='Anonymous' WHERE author='$dbname'");
					$db->query("UPDATE ".X_PREFIX."threads SET author='Anonymous' WHERE author='$dbname'");