Turn Off Firestick. To turn off your Firestick device, you can either switch the power off, pull out the power adapter from the power outlet, or remove the power cable out from the Firestick itself. The Settings menu also lets you put FireStick to sleep.
You'll find it on the upper left side of the remote. If you have a CEC-enabled TV, you should be able to use your Firestick to control its functions. It is not doing much of anything just sitting there connected.
Also, the newest versions of the FireStick remote have an included power button.
Is your Firestick keeps rebooting or fire stick keeps restarting at its will?
Again, you are not actually turning the device OFF, you are just sending it to sleep mode. Reboot your Firestick: Rebooting your fire stick will help in eradicating all the small errors that might be a reason for such a problem. To turn off Prime Photos, go to Settings > Applications > Prime Photos and turn off both Allow Guest Connections and If you turn off all of these settings, it will not only improve your security, but will.