Disclaimer : Rooting your phone Voids your phone warranty. I'm not responsible if you Brick your device.
Read this before Rooting :
1. Download and place all the files on your Desktop.
2. Install the LG Drivers you downloaded on your PC.
3. Extract files from the o4xr archive to your Desktop.
4. Connect your device to your PC using the USB cable.
5. Copy the APK file you downloaded over to the root folder of your phone’s SD card.
6. Disconnect the device after you have copied the file.
7. On your device, go to Menu>>Settings>>Security and enable Unknown sources.
8. Open My files on your device and tap on the APK file you copied earlier. It should install the app, finish it and then go to the next step.
9. Enable USB debugging on your device by going to Menu>>Settings>>Developer options>>USB debugging.
10. Launch the app you installed at the Step-8 from the App Drawer.
11. When the app launches, just press the Power button on your device for 3 seconds and choose Power OFF & Restart.
12. Connect the device to your PC when it restarts. Make sure to choose the Charge only mode if asked.
13. Open a Command Prompt Window on your Desktop by pressing and holding the Shift button on your keyboard and right-clicking on any empty area on the screen, then choose Open command window here.
14. Enter following command in the Command Prompt Window:
15. It should root your device. Your device should reboot as soon as the rooting is done.
16. When your device reboots, uninstall the SystemBackupTest app you installed.
17. Your device should be rooted now!