Do I need to factory reset to root galaxy note 4 SM-N910V?
Samsung devices usually have no locked bootloader so you won't remove that. Official updates do however remove any trace of a working root.Your device is nowhere near a developer device but more a custom device served with a custom firmware of Verizon noticeable on the V in your model no.

Because of that custom Verizon model it is possible that the bootlader may be locked as you can see in the log where it says &lt;ID:0/003&gt; FAIL! (Auth).
This means you are not authenticated to flash anything on your device which leads me to the assumption that your bootloader is Verizon-specific and therefore locked.