If the printer 100% finished the last print job successfully, the filaments should have been automatically withdrawn out of the hot-end by the 3D printer, so you don't need to preheat the nozzle before unloading the filament.
You just:
If last time you cancelled the printing task, one of the two filaments is still in the hot-end, so you will have to preheat the nozzle before removing the filament.
Preheat and Pre-extrude before unloading the filament