AMD really needs to update that tutorial as if you install "over the top", it uninstalls the old driver
anyway without having to uninstall first. It has done this since around the time the 10.2 or so came out.
As far as Driver Sweeper goes, as long as you're prepared for the risks involved in using it, go right ahead. Just make sure to have a good backup plan in place if it decides to screw up (remove more than it should, rendering you unable to install a driver at all), you can restore it back without having to completely re-install Windows to fix it. It doesn't happen often, but I have seen it enough over the years that I will never recommend using it.