It marks a sad end to Boothroyd's time in charge at Sixfields as a recent, slow but steady, upturn in form was blown away by the Chairboys who scored twice in the opening 15 minutes.
With all three Town substitutes having been used by half-time, a fightback sparked by Izale McLeod's goal was ended by a further injury to which Wycombe added insult with two more goals against the ten men.
A club statement gave the bare news of Boothroyd's exit less than an hour after the game with spokesman Gareth Wilsher addressing the media instead of the manager.
Boothroyd arrived at Sixfields intent on regaining the reputation that saw him tipped for the top while with Watford, and steered Town away from relegation trouble before last season's run to the play-offs.