I'm just putting this here so it will show up in search results. If you want to disable Wi-Fi Direct on the Roku 2, follow these steps:

  1. Go to home
  2. Settings
  3. System
  4. Advanced system settings
  5. Device connect
  6. Disable Device connect

If you're monitoring local networks, you should see the Roku network disappear. On my network, the Roku network was hidden, but I was still able to see it in this app until following the instructions above.

My Roku is running software version 7.1.0.

In case anyone finds this page and wants to know why you would want to do this: The Roku creates its own Wi-Fi network to allow certain kinds of remotes to connect to it. This wouldn't bother me, except it uses the same channel as the network you connect it to. Wi-Fi networks can work on the same channel, but they will cause performance problems for each other, even if one has very little traffic. Also, every additional Wi-Fi network is a potential security hole.