1. Press Home.
2. Scroll to Settings and press OK.
3. Scroll to System and press OK.
4. Scroll to Screen mirroring and press OK.
5. Scroll to Screen mirroring mode and press OK.
6. Scroll to Prompt and press OK.
This will bring a warning message up at the bottom of the screen when a device is trying to connect to the Roku TV
7. When a device tries to mirror on the Roku TV which you wish to block, select Always block and press OK.
8. To unblock a device press Home.
9. Scroll to Settings and press OK.
10. Scroll to System and press OK.
11. Scroll to Screen mirroring and press OK.
12. Scroll to Screen mirroring devices and press OK.
13. Scroll to the blocked device and press OK.
14. Press OK to unblock the device.
15. The device has now been unblocked. Press Home to return to the Home menu.