Will rooting delete my phone data?

Do I have to factory reset my LG G5 to root it? I want to root my phone but I don't want all my data deleted.

Are you willing to risk losing all your data with an attempted root? Back up your data first before messing with the OS. That should go without saying.

You do not have to FDR your device to root. HOWEVER you take a risk of losing all saved data by rooting your device. If you have a failed attempted of rooting and get in a soft brick, you would have to reflash stock firmware which will wipe all user and system data. If you do root and flash a custom rom, you must wipe data so you would lose your saved data.

If you don't know what rooting does and how it works, don't root. Research first.