Only way I know is to sand it out to a feather edge, re-prime and repaint and redo the clear coat. With careful work sanding with wet/dry paper used wet in 800-1100 grits you can blend it in pretty well.
Sand, prime and paint. I just started my cowling, its not to hard but I have OCD and for a first project I've been too patient/technical with it. I figure the hell with it its a jeep and its gonna get beat up just a little.