Doing a factory reset has some advantages for a few purposes. One of the big ones is wanting to remove all Data from the device.
This is handy if you plan on giving the device to someone else and don't want to give them your contacts or any other information.
In some circumstances it can even be handy to just start over especially if you have some minor issues and you assume the issues are Data related. If rooted its a great way to wipe the Data and Cache area's to prepare to change the ROM of the device.
1. Lets get started, press and hold power button to turn off your device.
2. When your phone is turned off you have to press and hold both Volume down button and power button at the same time.
3. Wait for LG logo to appear and let go off the buttons.
4. Now there should be a recovery mode menu on your screen.
5. Now use your volume keys to navigate to wipe data/factory reset option and select it with power button to finish the process.
6. And this is it! Now you know how to perform hard reset on your device.