Found the answer to my question
LG G2 lets you uses an LED light on the top front of the device and one at the back side (around the power button). To customize the Notifications to be informed by these LED lights, go to Settings > Display > Notification LED, make sure the feature is enabled and enable/disable following items:
For Front Side LED: Incoming call, Missed call, Missed messages, Missed LG emails, Missed cell broadcast messages, Alarm, Calendar notification, and Battery charging.
For Back Side LED: Incoming call, In call, and Alarm.
09.-How-to-Customize-LED-Lights-for-Notifications-on-LG-G2 Go to settings>Display>scroll down to Notification Led and tap>Rear Led and deselect all but camera face detection. This will stop the power button LED from flashing