To change the Meta block, you need to edit the file located in the \wp-includes\default-widgets.php directory of the site.
The Meta block code starts around line 313. There may be some changes in different versions of WordPress.
It looks like this:
<ul>
<?php wp_register(); ?>
<li><?php wp_loginout(); ?></li>
<li><a href="<?php bloginfo('rss2_url'); ?>"........
<li><a href="<?php bloginfo('comments_rss2_u........
<li><a href="<?php esc_attr_e( 'http://wordp........
/* translators: meta widget link text */
_e( 'WordPress.org' );
?></a></li>
<?php wp_meta(); ?>
</ul>