Type the next command, this will put the LaunchPad back to its original setup and will take all programs out of folders.

sqlite3 ~/Library/Application\ Support/Dock/*.db 'DELETE from apps;' \ ' DELETE from groups WHERE title<>""; DELETE from items WHERE rowid>2;' \ && killall Dock

However, it should be noted that the folders will not disappear. To get rid of them, simply load at least one app into Launchpad, then drag the app into & out of the folder. It will 'evaporate' when it's empty.

If you want to do a full reset of the LaunchPad, I will create another guide for those steps.