User::CleanUsername PHP Method

    public static function CleanUsername($username)
    {
        return preg_replace('#[^A-Za-z0-9' . preg_quote('-_@. ') . ']#', '', $username);
    }

// Logout
//////////////////////////////////////////////////////////////////
if ($_GET['action'] == 'logout') {
    session_unset();
    session_destroy();
    session_start();
}
//////////////////////////////////////////////////////////////////
// Create User
//////////////////////////////////////////////////////////////////
if ($_GET['action'] == 'create') {
    if (checkAccess()) {
        if (!isset($_POST['username']) || !isset($_POST['password'])) {
            die(formatJSEND("error", "Missing username or password"));
        }
        $User->username = User::CleanUsername($_POST['username']);
        $User->password = $_POST['password'];
        $User->Create();
    }
}
//////////////////////////////////////////////////////////////////
// Delete User
//////////////////////////////////////////////////////////////////
if ($_GET['action'] == 'delete') {
    if (checkAccess()) {
        if (!isset($_GET['username'])) {
            die(formatJSEND("error", "Missing username"));
        }
        $User->username = $_GET['username'];
        $User->Delete();
    }