To disable the popup with a request to rate plugin you should add the following code to the functions.php file of your active theme:
$su_notices = get_option( 'su_option_dismissed_notices', array() );
$su_notices['rate'] = true;
update_option( 'su_option_dismissed_notices', $su_notices );
Open main page of the site. After opening the site main page, the code above code can be removed from the functions.php file.
Rating window will not pop up on your site again.