<?php
  if(session_id() == '' || !isset($_SESSION)) {
    // session isn't started
    session_start();
  }

  if (!isset($_SESSION['userid'])) {
     $_SESSION['message'] = "Must login before can deregister";
     require('index.php');
     return;
  }

  $db = new SQLite3('user.db');

  $command = "DELETE FROM user WHERE userid='" . $_SESSION['userid'] . "'";
  $result = $db->exec($command);

  if ($result) {
    unset($_SESSION['userid']);
    unset($_SESSION['logged_in']);
    $_SESSION['message'] = "Registration cleared";
    require('index.php');
  }
?>