Free application <b>Off</b> will lock your screen.
With <b>Off</b> you can lock your screen with 1 tap. With "Off" you can reduce the amount of times you press the power button to extend your device's life.
<b>Note:</b> Before uninstalling you have to go to "Settings" -> "Security" (or "Location & security" ) -> "Device Administrators" and make the "Off" app unchecked.</br></br></br></br>