From the netflix main screen go to settings. Then press reload Netflix. That will take it away. Idk how to put it there though.
I have a Roku Express, and had the non stop dialog box in the top left of the screen when watching Netflix. Couldn't get rid of it until -
1. While watching your show, exit out
2. Return to main netflix menu
3. Click the * button 3 times quickly
4. You should now hear "audio _________________ diasbled"
5. Go back into your show, and enjoy