Where are the marketplace asset installers stored on my computer?

[ClockworkOcean]

Look at the settings in the launcher

That’s where it’s all stored.

If you upgraded from 4 to 5, there will also be a lot of 4 stuff, quite possibly on another path. You can find errant things like this with something like

http://www.uderzo.it/main_products/space_sniffer/