Remove door and bed gone wrong in Dwarf Fortress

Solution 1:

There's no problem here actually. While it's true that there is a door at that place, it isn't a build door, it is an item.

You can see it if you look with k, when a dwarf deconstructs a building they will drop the components where they're standing, then when there is space in a stockpile it will be moved to the stock pile.

Make a furniture stockpile with enough room in it and the door (and bed) will be picked up when a dwarf is done drinking and resting and not doing what you want.

Also, the reason d-b-c (claim) doesn't work is because the door was never forbidden, it was just dropped and no one bothered to pick it up yet. =p

Solution 2:

As Kevin said, the door is not built. If you really want to move it from there anyway, you can mark it for dumping: d-b-d