As shown in video 14

>>>>> Add these codes to the bottom of the themes functions.php file. If you have a child theme then add it there. Any custom work should always be done in a child theme because when you update the core of WordPress these custom additions may be over-written. 

But even easier is using the code snippets plugin as shown in video 14

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// remove wp version meta tag and from rss feed
function at_remove_wp_ver_meta_rss() {
    return '';
}
add_filter( 'the_generator', 'at_remove_wp_ver_meta_rss' );


// remove wp version param from any enqueued scripts
function at_remove_wp_ver_css_js( $src ) {
    if ( strpos( $src, 'ver=' ) )
        $src = remove_query_arg( 'ver', $src );
    return $src;
}
add_filter( 'style_loader_src', 'at_remove_wp_ver_css_js', 9999 );
add_filter( 'script_loader_src', 'at_remove_wp_ver_css_js', 9999 );