codeigniter session

set session data
$newdata = array(
        'username'  => 'johndoe',
        'email'     => '[email protected]',
        'logged_in' => TRUE
);

$this->session->set_userdata($newdata);

unset

unset($_SESSION['some_name']);

// or multiple values:

unset(
        $_SESSION['some_name'],
        $_SESSION['another_name']
);

retrieve session data

$this->session->userdata('item');