Wordpress by default shows the version of Wordpress being used in the site as well as the feed.
Unless and until you are up to date with the latest vesrsion of wordpress its never a good idea to show the version number specially it provides loop hole for hackers to hack into the website.
The easiest and proper way to hide the version of WordPress is by adding the block of code below in the functions.php file of the current theme.
[code language="php"]
function wpguru_remove_wpversion() {
return '';
}
add_filter('the_generator', 'wpguru_remove_wpversion');
[/code]