Mac OS X Lion’s Launchpad sometimes can be very buggy. In my case, I saw an app appears twice in my Launchpad. Nonetheless, this app could not be removed from Launchpad since it was downloaded and installed outside of the App Store. So, even I had tried to refresh the Launchpad, the app refused to be removed from the Launchpad. The whole idea of removing the app from Launchpad is to stop the app to appear twice in the Launchpad. Once the app is removed from the Launchpad, one can always drag the same app back into Launchpad, but this time it won’t appear twice! For those who are worrying that removing an app from Launchpad might actually uninstall the app, it’s not so!
Anyhow, enough with my ranting, and here is the solution. You need to enter the command line (sqlite3 ~/Library/Application\ Support/Dock/*.db “DELETE from apps WHERE title=’APPNAME’;” && killall Dock) and replace the parameter where it says title=’APPNAME’ with the name of the app that you’ve wanted to remove. So for an example, if you want to remove Spotify from Launchpad, you type in (sqlite3 ~/Library/Application\ Support/Dock/*.db “DELETE from apps WHERE title=’Spotify’;” && killall Dock). Once you have done the removing of the app from the Launchpad, you might want to go back into Finder > Applications and drag the app you have removed from Launchpad back into Launchpad (i.e., appearing on the Dock). Remember, doing this correctly, the same app won’t appear twice again inside your Launchpad.