Every time you areusing the Power On/ Off button to lock the iPhone 6, you will hear a sound that announces you that the lock screen is activated. If you lock the iPhone 6 often manually, then this lock-soundannoys you after a short time. So it can be that one would like to disable this sound when locking the iPhone 6. If you do not know how this works in iOS, then we would like to explain this in our article here.
To do this, navigate to the following submenu of your iPhone 6:
From the home screen of the iPhone 6 go to: Settings --> Sounds
Scroll all the way down in this submenu. Here you will find the option "Lock sounds". Disable the option via the controller.
When you activate the lock screen on your iPhone 6 using the Power On/ Off button you will now hear no sound.