Unless I'm completely misunderstanding the question, I'm seeing a "Remove" button directly to the right of the item in the alcove in the editor, outside of any scripting environment. ... ... ... yeah I'm probably misunderstanding the question.But now my new problem is that I don't know how to remove an item from an alcove
Unless you didn't add it to the alcove itself, and just added it on top of the alcove, separate from it, yet occupying the same physical position. .... in which case, it's possible to click on the alcove and add items there in the properties panel actually. To remove items occupying the same space, clear your selection by clicking in a blank area of the map, then click on it again, and it'll provide a pop-out to select which item you'll be interacting with, since both are clumped together.