There are a few things you can do to clean burnt greenpan. The first is to pour a pot of boiling water onto the pan and set it on the stove to boil. Then, use a plunger to suction onto the top of the pan and pull until all of the liquid has been removed. Next, use a paper towel or cloth to dry off the pan. Finally, put some cooking oil in a frying pan and heat it over medium-high heat. When hot, add the greenpan and cook until browned on both sides.