Mac: Lion's Launchpad feature is a handy way to quickly launch apps, but when it's filled with every program in your app directory, it becomes a little less useful. Macworld shares a way to completely remove everything from Launchpad and start fresh.
If you just want to get rid of apps, you can hold down the Option key with Launchpad running and delete a few select apps. If you want to start with a totally clean slate, you need to wipe out the contents of the database with a Terminal command:
sqlite3 ~/Library/Application\ Support/Dock/*.db "DELETE from apps; DELETE from groups WHERE title<>''; DELETE from items WHERE rowid>2;"; Killall Dock
Now Launchpad is completely empty, so you can customise it as you see fit by dragging apps directly to the Launchpad icon in the Dock. It's a handy way to make Launchpad a bit more useful than the Applications folder you already have.
Clean out Launchpad completely [Macworld]