In any case, you can turn off the mChat from your User Control Panel if you would prefer not to see it. Navigate to the mChat tab and just click it off by checking "No" in the first option. You can re-enable this at any time if you change your mind. This only removes it from the Index page so if you want to remove it from your index page so you don't have to see it but still want to pop in from time to time, you can click the mChat page at the top of the forum and go to it.
Some styles allow you to collapse the mChat on the Index page without going to the UCP, but this is the way most folks will have to do it since ProSilver and ProLight are not one of those styles.