Currently, it integrates users (just install CB and simpleboard tab as per installation docs and Kunena as per installation docs) but a full integration is coming... the Kunena and CB devs are working on it currently.
You should be find the way it is... Kunena uses CB Login now. If you do want to get rid of that area of the forum, you need to change it in the forum CSS or find profilebox.php if it hasn't changed since Fireboard.