Remove the headliner.
Disconnect the front drain tubes (A) and the rear drain tubes (B). Detach the tube clip (C).
With an assistant holding the frame (A), remove the bolts, then remove the frame.
Honda Odyssey Service Manual > Moonroof Frame and Drain Tube Replacement: Rear Middle Drain Tube Replacement Remove the rear middle drain tube (A) from the frame (B). AB ...