Create Session and Remove

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

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

//In PHP, we can remove data stored in session using the unset() function as 

unset($_SESSION[‘some_name’]);

//If you want to remove more values from session or to remove an entire array ,
you can use the below version of unset_userdata() function.

$this->session->unset_userdata($array_items);

// for reference use this links--
https://www.javatpoint.com/codeigniter-login-form