Hiding a category from recently published posts in WordPress

To hide a category and its posts from recent posts:

1. Get the category id(s), (for example 3)
   
2. Find index.php
   
3. Paste the following code just before *’THE LOOP’.
   

    

   <?php query_posts(‘cat=-3’); ?>

   Note: Please take a backup of your index.php before doing this.
   

*THE LOOP: Although it may differ in some cases, the basic loop would look like this –

<?php if (have_posts()) : while (have_posts()) : the_post(); ?>

Source:

http://www.tips4developer.com/wordpress/wordpress-hide-post-specific-category-post-page/