The gcode to purge the material in the tube to the printing tip is:
G0 Y100 F100
You can modify the Y value to adjust speed and F to adjust the duration of extrusion. Be careful not to go too fast for a very viscous material, as it will cause stress to be built up in the system.
REPEAT: DON’T PURGE TOO FAST, IT MAY LEAD TO STRESS BUILD UP AND FAILURE OF THE DISCOV3RY.