[As Kees said][1], running 
`unity --reset` 
will reset all of the launcher *options*, but it won't remove your custom favorites. To also remove any launchers you've added to the springboard, run 

    gsettings reset com.canonical.Unity.Launcher favorites

I would recommend running the gsettings command before `unity --reset`, so that you won't have to restart unity for the gsettings key reset to take effect.

  [1]: http://askubuntu.com/questions/17610/how-do-i-reset-my-unity-configuration/17614#17614