How to unpair the app and TV and then how to uninstall and reinstall the TV app on Apple TV
1) Locate the settings menu on your iPhone by clicking the hamburger menu in the upper right hand corner and then selecting "Settings".
2) Under "Activate a display" find the display you have connected and click the "x" next to it to disconnect the pairing between devices.
3) Next, exit out of the application to your home screen on your device. Delete the application from your iPhone by holding down a finger on the app until the option to "remove" the application appears.