Out of the Dark
(1989)

Kevin Silvers (Cameron Dye) is Bobo the killer clown. He is found out when Ruth Wilson (Karen Black) finds his mask. When he starts strangling her, she shoots him repeatedly, before Lt Frank Meyers (Tracey Walter) shotgun blasts him repeatedly out of a window to fall several stories to the ground (the final shot shows him sprawled amongst broken glass, dressed as Bobo)

Thanks N.D. Woods!