It is quite hard to find the way to restart and reboot an Apple TV for a new user. How to do?
How to restart an Apple TV?
Go to Settings app on Apple TV --> Access System --> Choose Restart from the list.
At for some old Apple TV models, you might need just go to Genera --> Restart
We are actually able to force reboot Apple TV using the remote
Hold down the Menu button and Home buttons concurrently until you see the light flash.