Finally I find solution to hide that particular category which is showed in front end,
I use this code to hide the selected category front end : Function.php
add_filter('get_the_terms', 'hide_categories_terms', 10, 3);
function hide_categories_terms($terms, $post_id, $taxonomy){
// list of category slug to exclude,
$exclude = array('computer');
if (!is_admin()) {
foreach($terms as $key => $term){
if($term->taxonomy == "category"){
if(in_array($term->slug, $exclude)) unset($terms[$key]);
}
}
But any answer for how to get RSS feed by using custome field will be more appreciated .