The bootloader is that element in your Android operating system that you have to unlock if you want to flash custom software into your device, and most manufacturers lock it for that very reason – they want you to enjoy the device as they meant it to be used. But the spirit of Android is in the customization, so some manufacturers allow the official unlocking of the bootloader with certain devices. LG is one of those.
LG has just included the LG V20 – that is, the US variant – to the supported devices where they are allowing unlocked bootloaders. This means that if you are an LG V20 user and you want to flash a custom ROM or gain root access to this device, then there is a way for you to unlock the bootloader without any more hassle than you have to endure. But take note that this is for the US variant only (US996).
The instructions to officially unlocking your LG V20’s bootloader are pretty simple, but they are precise. You need to follow the instructions stated at the source link below, which includes getting unlock keys from LG which will be emailed to you to facilitate the unlock. You also need to have your device’s unique IMEI number ready.
If you have an LG V20 and you’ve been itching to use a custom ROM or some “root only” tweaks, you can unlock the bootloader with this process. Just make sure you understand that unlocking the bootloader will VOID YOUR WARRANTY.
SOURCE: LG Developer site