It is "K2 Categories" used as menu item for initial page (K2 » Item listings » Categories).
You can create it in Joomla menu items -> New- > Select menu type -> K2 -> Categories. Then, in Options tab select categories which items you want to show. Then, you just need to assign filter module for this menu item.
Ok now the category's items appears when we come the first time on the page but when we click on the search button, those items dont disappear, so we have on the page both the results + the category's items.
How do you do to hide the category's items after clicking the search button and just display the items results.