Joomla how to disable cookies for normal user

You must edit two files /libraries/src/Application/CMSApplication.php and libraries/joomla/session/handler/native.php

In libraries/src/Application/CMSApplication.php change code around line 166 and add if condition for whole code in method if (substr($_SERVER , 0 , 14) == "/administrator"){

public function checkSession()
    {
      if (substr($_SERVER['SCRIPT_NAME'] , 0 , 14) == "/administrator"){ // added condition
        $db = \JFactory::getDbo();
        $session = \JFactory::getSession();
        $user = \JFactory::getUser();

            // ... rest of code
      }
}

In libraries/joomla/session/handler/native.php change code around line 229 add if condition for whole code in method like in previous file

private function doSessionStart()
    {
      if (substr($_SERVER['SCRIPT_NAME'] , 0 , 14) == "/administrator"){ // added condition
        // Register our function as shutdown method, so we can manipulate it
        register_shutdown_function(array($this, 'save'));

        // ... rest of code
      }
 }

This works in Joomla 3.8.2