You can trash items from a collection with the same shortcut you would use to trash them from the binder. Emphasis on “trash” though, not destroy. It is impossible to outright delete a binder item in one move.
But even trashing won’t happen by dragging a bookmark into the list. Worst case the collection list lost track of an item (some kind of bug), but it’s just a list of items, not the actual items themselves. We’d need some manner of reproduction checklist to verify the bug.