Are you solely trying to delete it through Launchpad? If so, that's your problem. Use Finder and navigate to the Applications folder (or use the short cut Shift+Cmd+A) and delete it from there.
I honestly think that Launchpad is only creating more confusion for newer users and switchers than it's solving. The whole disconnect between the applications folder and the Launchpad UI creates problems like this that really shouldn't exist.