Not modifying any doorway. Removing the door an frame an maybe a hack stud. Move the cage in an rehang the door. Clean up would take longer then removing the frame. Removing a jack stud is five minutes, less with a Sawzall.
I still say call the builder an take it a part.
Good luck!
Unfortunately for this enclosure it isn't just remove screws and cut.
Also. We aren't talking about length here. We are talking width.