I want to ask, if my game jam is already over and as a host I'm reviewing  the submissions but then accidentally  clicked 'remove submission' on one of the games, I found that I can still access the game page but the game itself is no longer in the game jam submissions list. Can this be recovered? Can I have that game back as a submission?

You will have to get a late submit link from the host in order to re-add your game to the jam. The host can generate this on their jam’s edit page, if you provide them with a link to your game.