As @KnightWold very well said, if you are the copyright's holder you can file a DMCA and steam will act quickly on those.
As for the unity store, it's a bit more complex, and assets flippers know that very well.
If the unity tutorial owner agrees on having his work sold as is (Me thinks he will not like it much), you can't do much.
Stupidest thing is these guys are not gonna be able to make that shovelware drops cards...
Steam's "confidence metric" dictates that to be able to drop cards, the game in question needs to reach an (undisclosed) number of copies, in order for it to start dropping trading cards (wich valve takes a cut of).
It THE thing those "devs" want. Then provide their bot farms with easy money, make a few GA's to give the impression it's people playing.
But still, they keep filling up the storefront with pure s***
And btw this is the very definition of an asset flip, regardless if it's a free tutorial for unity or not.
The number of these "game-like objects" like valve calls them is by the thousands by now, thanks to again, steam direct.