Solved How To Uninstall Program That Won’t Uninstall

“unins000.msg” is an InnoSetup “log” of items that were installed, in which location, what shortcuts were created, and changes made to the registry. For that “unins000.msg” to be missing, one can assume that it was manually deleted… and that likely suggests attempting a “manual un-install” of the rest of the program, at least to the point where a fresh install-and-uninstall is plausible.

Here is a pretty good generic how-to on performing a “manual uninstall”:
How-To Manual Uninstall.