It will happen that the robot runs away. Indeed, if you stop your program, the robot does not stop. It keeps executing the last command it got. To stop the robot in case of emergency:
‼️ Lift the robot a few centimeters from the floor. If the wheels stop making contact with the floor the robot will stop.
It might happen that your robot stops responding to commands. In this case, you can reset the robot.
If this does not work, there is a more drastic way. The bottom plate of the robot can be removed and the battery can be disconnected. You will need to ask instructor assistance for removing the battery.