How to remove screen options from wordpress dasboard

Remove screen options from dashboard in wordpres,you need to write bit of code in your wordpresss
functions file.here is code;

Remove screen

<?php add_filter('screen_options_show_screen', '__return_false');?>

Remove help tab

<?php  function remove_help_tabs( $old_help, $screen_id, $screen ){
    $screen->remove_help_tabs();
    return $old_help;
}
add_filter( 'contextual_help', 'remove_help_tabs', 999, 3 );
?>