HDMI audio output creates 3rd Monitor



I am using an AMD R9 200 series with two matching HP 24" monitors. I recently used the spare HDMI output from the card to connect to my Onkyo amplifier to get high end audio. The problem is that now Windows thinks I have three monitors, and every time my cursor goes off the right edge of my second monitor, it disappears into the 'HDMI' monitor (monitor 2 in the images below).


Ie there any way to disable the HDMI monitor in either Catalyst or Windows?