define( 'COOKIE_DOMAIN', '' );

define( 'ADMIN_COOKIE_PATH', '/' );
define( 'COOKIEPATH', '' );
define( 'SITECOOKIEPATH', '' );

define( 'COOKIE_DOMAIN', 'example.com' );
define( 'ADMIN_COOKIE_PATH', '/' );
define( 'COOKIEPATH', '/' );
define( 'SITECOOKIEPATH', '/' );

define( 'COOKIEHASH', 'unique_cookie_hash_string' );

// Cookies
define( 'COOKIEHASH',        md5( 'yourdomain.com' ) );
define( 'COOKIE_DOMAIN',     'yourdomain.com'        );
define( 'ADMIN_COOKIE_PATH', '/' );
define( 'COOKIEPATH',        '/' );
define( 'SITECOOKIEPATH',    '/' );
define( 'TEST_COOKIE',        'thing_test_cookie' );
define( 'AUTH_COOKIE',        'thing_'          . COOKIEHASH );
define( 'USER_COOKIE',        'thing_user_'     . COOKIEHASH );
define( 'PASS_COOKIE',        'thing_pass_'     . COOKIEHASH );
define( 'SECURE_AUTH_COOKIE', 'thing_sec_'      . COOKIEHASH );
define( 'LOGGED_IN_COOKIE',   'thing_logged_in' . COOKIEHASH );

function clear_session_on_logout() {

$current_user = wp_get_current_user();

// get all sessions for user with ID $user_id
$sessions = WP_Session_Tokens::get_instance($current_user->ID);

// we have got the sessions, destroy them all!
$sessions->destroy_all();
}
add_action('clear_auth_cookie', 'clear_session_on_logout');