In this paper, the supervisory control of a Discrete Event System (DES) analyses states and events to construct an autonomous package delivery system. The delivery system includes a legged robot in order to autonomously navigate uneven indoor terrain and a conveyor belt for transporting the package to the legged robot.The aim of the paper is using the theory of supervisory control of DES to supervise and control machine's state and event and ensure robots autonomously collaborate. By applying the theory, we show the collaboration of two individual robots to deliver goods in a multi-floor environment. The obtained results from the theory of supervisory control are implemented and verified in a simulation environment.