You can't alter the main block of icons (Kodi/Chrome/Youtube/Play Store/Media Center) with current launcher. Himedia have plans for a new launcher which will be more customisable, but it's not made it into the new firmware released today. Probably next firmware.
With current launcher you can add/remove apps along the bottom of the screen.
An alternative would be to replace the Himedia launcher completely. Q5/Q10 can use any Android launcher and there are loads. Search 'launcher' in Play Store. Good options are Nova, Apex, Asus Zen.. These are all very / completely customisable.