DDU 1st is always better for a clean removal.
I you use custom bioses, don't forget to patch the 18.3.4 driver before the reboot.
Drivers 18.x.x don't need patch. AMD removed check mod bios. I'm use RX 580 8Gb and didn't patch drivers from 17.12.x when AMD was removed mod bios protection... All my 580 cards use modded bioses.
RX580 is not checked, but RX480 is, and needs the patch
Thank you all for the hint. I am on 580 so I won't patch. However, I noticed in the past when I clean install AMD drivers from Clean Windows, it installed much quicker (screen flick 4 times per GPU) than upgrade (it seems AMD is removing old driver on each GPU one-by-one in the background The screen flicking hundreds of times before completion and sometimes OS hang during upgrade).