I removed the file because I didn't want people buying from this page anymore
I don't know of a way to keep the file but having it unlisted so yeah the only way is to get it again or find it on a pirate site somewhere
I, like many others, have come here from the bundle.You should be able to set the game to Restricted, which will allow people who own the game to download it, but will disable people who don't own the game from being able to buy it new.
https://itch.io/docs/creators/access-control