Thank you! It's currently not possible to remove items but I agree that they should be. I might add that in the future.
Be careful though. At first I was kinda annoyed by the game not allowing to sell a slot. But then I realize that this is meant to be speed run, with limited slot that the player need to think since the start of the game.
So depending on how you meant this game to be, that feature could be a detriment to the fun.