How do you pump diesal out of your gas engine?

The entire fuel system needs to be completely drained. Remove the tank and replace the fuel pump and screen. Replace the fuel pressure regulator. Replace any fuel filters. Remove the injectors and clean, Remove the fuel rail and clean. Diesel does NOT belong in a gasoline engine. Any attempt to run it will possible destroy it. It may not run at all, which it probably the case but if there was gasoline in the tank when the diesel was put in, it won't run very long without causing severe engine damage.