In order to hard reset a LG KS20, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
LG KS20 device will be brought back to the default configuration of a brand new device.
1. Turn off the phone.
2. Now press-hold the Volume Down, Power and Call buttons.
3. Hold them for ten seconds after LED flashes. Done!