You need to hook a couple (or maybe more) things:
/* hide category from shop pages */
add_action( 'pre_get_posts', 'custom_pre_get_posts_query' );
function custom_pre_get_posts_query( $q ) {
if ( ! $q->is_main_query() ) return;
if ( ! $q->is_post_type_archive() ) return;
if ( ! is_admin() ) {
$q->set( 'tax_query', array(array(
'taxonomy' => 'product_cat',
'field' => 'slug',
'terms' => array( YOUR-CATEGORY-SLUG, YOUR-CATEGORY-SLUG-2 ), // Don't display products in the knives category on the shop page
'operator' => 'NOT IN'
)));
}
remove_action( 'pre_get_posts', 'custom_pre_get_posts_query' );
}
Change, obviusly YOUR-CATEGORY-SLUG, YOUR-CATEGORY-SLUG-2 for your cat or cats to hide from shop pages.
Then, you need to hide them from menues too, right?:
/* hide category from menues */
add_filter( 'get_terms', 'get_subcategory_terms', 10, 3 );
function get_subcategory_terms( $terms, $taxonomies, $args ) {
$new_terms = array();
// if category and on the shop page (change it with is_woocommerce() if want to hide from all woo pages)
if ( in_array( 'product_cat', $taxonomies ) && ! is_admin() && is_shop() ) {
foreach ( $terms as $key => $term ) {
if ( ! in_array( $term->slug, array( YOUR-CATEGORY-SLUG, YOUR-CATEGORY-SLUG-2 ) ) ) {
$new_terms[] = $term;
}
}
$terms = $new_terms;
}
return $terms;
}
But i don´t think this solve 100% the thing, since then, what about search results?