If the nut and ignition rotor have been removed it should just slide out of the bearing.
It might require a couple taps on the end of the crank. Use a hard plastic hammer or thread the nut back on half way and tap squarely on that. You need to be careful not to damage the threads on the crank.
What are you trying to accomplish? If you just wanted to removed the piston from the rod, splitting the case wasn’t neccassary. Pull the clips that hold the wrist pin in and push out the pin. If you’re replacing the rod, the crank has to come apart. For help on line, GIF is going to be your best resource. If you need a shop to help you out, LAD Specialties is not that far of a drive.
LAD Specialties customer / tony kart / rotax / kt100