The uninstall process requires software downloaded from ASUS, it is the Armoury Crate Uninstall Tool and can be found in the downloads for your motherboard.
Using the Windows uninstall process does not work.
From the ASUS Support Center, select your operating system then click Show all in blue, it's the third download.https://www.asus.com/supportonly/Armoury%20Crate/HelpDesk_Download/
If using the uninstall tool fails, or does not fix the issue after you reinstall, there may be a need to reinstall Windows (ugh, it sucks but it does clean out the Armoury Crate garbage left behind from old versions). I had to do the reinstall that wipes the drive to get a working AC, so be sure to have backups of everything.
If you are unable or unwilling to reinstall Windows, then Signal RGB is available https://www.signalrgb.com/download/
for free or pay. It seems to work pretty reliably. The updates to it don't break everything, so there is a big bonus.