How do I delete an app purchased through the Mac App Store?
There's no delete mechanism in the App Store. You can use a normal app-removal procedure to get rid of it. Apps leave config information and what not lying around that's outside of the .app container, so just dragging the .app container to the trash doesn't uninstall it completely. An uninstaller app like TrashMe will find and remove most of the little bits apps strew about your profile.