How do I completely uninstall it? I deleted the folder I created from the compressed file and everytime I try to redownload it, open it, it starts right back up in processing the files where it left off as if I never uninstalled it. And then it always freezes.

I have no idea what it is, but I would suggest you uninstall it, check for any ini files it may leave behind and delete them, any modification to any other ini or config files, any references to it in anything like LOOT, TES5Edit, WryeBash, NMM, MO or whatever, run a registry cleaner and then reboot.

Then, if happens again, contact the author.

I think it puts a lot of stuff in your system's registry. I was browsing the source code a few days ago and saw stuff like:

RegSetKeyValue(Settings, "Compression", "Quick", RRF_RT_REG_SZ, optimizequick ? "1" : "0", 2);

Yep. It was an educated guess that the registry may have been altered, as I have had similar experiences with other things, like a new install of Morrowind on my C:\ drive using settings from a back up copy on my E:\ drive from my old PC.

If you don't do a clean sweep, every time you re-install it it will keep the old settings due to the registry entries.

Which registry cleaner do you recommend for windows 10? Can I just delete them manually?

I doubt a registry cleaner would know what to do with them. I tried and failed to find them manually. Let me know if you can find them.

I have BitDefender Total Security Antivirus and it includes a registry cleaner.

There are free registry cleaners on the net but you have to be REALLY, REALLY, REALLY careful where you get them from and also take GREAT care when you install them to not install some garbage search engine or browser bar that you can never get rid off.

I'd have thought Win 10 should have it's own registry cleaner, and using Remove Programs should also restore the registry, but it probably does not. I still use Win 7 Home Premium 64 bit as it ain't broke, there's nothing to fix and it does not break a lot of games.

Going by this https://github.com/Ethatron/ddsopt/blob/master/gui/GUI.cpp, it looks like DDSopt would be here:

HKEY_LOCAL_MACHINE/Software/Bethesda Softworks/DDSopt

I only have Oblivion under Bethesda Softworks, probably because I initially installed it from a DVD before buying the GOTY edition from Steam. I scanned my whole registry for "DDSopt" and found nada.

See if you have any DDSopt stuff there.