Removing WordPress version number from the header and RSS
 
Open functions.php theme's file and add at the end

// Pick out the version number from header and RSS
function remove_wordpress_version() {
return '';
}
add_filter('the_generator', 'remove_wordpress_version');

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Removing WordPress version number from Scripts and CSS

Open functions.php theme's file and add at the end

// Pick out the version number from scripts and styles
function remove_version_from_style_js( $src ) {
if ( strpos( $src, 'ver=' . get_bloginfo( 'version' ) ) )
$src = remove_query_arg( 'ver', $src );
return $src;
}
add_filter( 'style_loader_src', 'remove_version_from_style_js');
add_filter( 'script_loader_src', 'remove_version_from_style_js');