MiniTool Partition Wizard Free is currently doing a "fill-sectors-with-zeros" pass so I can give this drive to my brother tomorrow and get on with my life. CCleaner was a good idea, but without support it's safer to go with the individual apps you can depend on for your privacy.
I wanted privacy. I paid for CCleaner. I tried to wipe a drive. None of my drives were selectable. I tried to get support. I was forced to register on a forum to ask other users for help. No developer support. Yeah, I'll be "exploring other options"...