How to uninstall Gigapixel?

I’ve accumulated numerous installations of Gigapixel including beta and non-beta versions. Unlike Sharpen, DeNoise, etc, the Gigapixel installations seem to lack an “uninstall.exe” program. Windows Apps&Features is unable to uninstall them without this, nor can I do a clean job manually.

I’d like to uninstall the older versions because they’re wasting large amounts of space on my drive. Another reason is to try to fix the problem of the Model Files failing to download. This has been a problem for the last several versions. I’ve tried everything including dealing with firewalls, antivirus software, etc. Downloading always fails whether it’s from the pop-up dialog or Help/Download_Missing_Model_Files. I’m guessing that uninstalling and re-installing Gigapixel should fix it. Unfortunately I’m unable to test that theory.