Open Control Center
Tap the Flashlight icon to turn it off
If using the Lock Screen flashlight shortcut, press and hold the Flashlight icon, then release to turn it off
If it’s on from the Camera app, tap the Flash icon in the Camera interface to turn it off
If it won’t turn off, open the Settings app
Go to Accessibility
Tap Touch
Turn off AssistiveTouch (if enabled), then try again via Control Center