Is it safe to delete the C:\ATI folder? It keeps adding up every time there's a new version. I was wondering if it's safe to delete all of them once the installation is complete?
You can safely delete it. When you install ATI drivers it first extracts the installer to C:\ATI\Support\ and then installs it. Every version of ATI driver makes a folder in C:\ATI\Support. These are only installers(in your case 3 different versions). You can even re-install the drivers from here.