Is there a post here covering ALL the things one can do to reset Vegas? The factory default, the menu to do all that cleaning, the manual files to delete from your USER directories?
That would be handy
Easy. Check out item 14 in https://www.vegascreativesoftware.info/us/forum/vegas-pro-faqs-and-troubleshooting-guides--104787/
User directories ... you probably have to do that manually because the user directories are not part of the program.
1. Reset VEGAS 
.
2. Use Geek to uninstall VEGAS Pro https://geekuninstaller.com/download & delete residues.
3. Use everything tool to search "VEGAS" / "Magix" / "Sony" in your system and delete them. https://www.voidtools.com/downloads/
4. Search "VEGAS" / "Magix" / "Sony" in regedit and delete those values & keys.
5. Reinstall VEGAS Pro.
Personal view, just for reference only.
2. Use Geek to uninstall
Revo Uninstall is another option the can uninstall and clear out the pertinent data.
Both Revo and Geek have pro and freeware versions.
Rather than Uninstall - which neuters all the various plugins that would need reinstalled again - I'd rather manually clean everything else out, full reset, remove cached stuff, but not full uninstall. Thanks, I'll check out the links and see if that covers it. I'm aware of factory reset, the menus to clean some things, and deleting files from user directory.
Here, @NickHope once did a lot of work and listed everything point by point - or is that no longer up to date?
@walter-i. Could well be out of date since VP18, now that some preferences have been moved.