Dell has quietly pulled the plug on its DJ Ditty music players, less than a year after the world’s largest computer maker launched the device to compete with Apple’s iPod Shuffle. The company stopped selling the Ditty on August 17, Dell spokesman Venancio Figueroa said Wednesday. He declined to characterize the decision as Dell bowing out in the face of competition from market leader Apple. Dell is trying to focus on its core areas of PCs, printers and flat-panel televisions, he said.