To undo, or remove fobulation; wishing someone had never acted in the first place.
Someone may fobulate (organise, or sort) something poorly; in a way which is not suitable or just plain unproductive. To defobulate, one removes this organisation allowing resumption of normal operation.
If the previous fobulation was productive, but a new one is needed for a specific purpose use refobulate instead of defobulate.
I finally defobulated the files after the intern decided to improve efficiency.