Free application Turn Off Screen (Please buy Turn Off Screen Pro to support developer: https://play.google.com/store/apps/details?id=ndt.mobile.android.turnoffscreenpro)
Easiest application, using only one click to turn off screen.
This app uses the Device Administrator permission.
Note: To Uninstall with 2 steps:
1. Go to "Settings" -> "Security" (or "Location & security" ) -> "Device administrators" -> uncheck "Turn Off Screen".
2. Uninstall app as normal.