Code to “noindex” Single Category in WordPress

/* No Index Single Category */
add_action('wp_head', 'wpflt_header_function_condition_noindex_single_category');
function wpflt_header_function_condition_noindex_single_category(){
if ( is_category( '1' ) ) { ?>
<meta name="robots" content="noindex" />
<?php }
}

With this filter we can avoid a single WordPress category from getting Indexed. Enter the category ID in line 4.