How can I turn the subtitles off?

Hey Christopher.  You have a couple of options.  If you need to turn them all off, the easiest way is probably just to turn them transparent.  Select the font color and more the transparency slider until they are invisible.
If you need to turn off specific ones, there is a switch.  Click the little 3 lined menu bar to the right of the box  and a menu appears.  Click Hide Box to hide the box around the subtitles.  Click Hide text to hide the subtitle text.
Thanks!
Craig