How to uninstall older version of Xcode

• Your XCode 4.x is installed in your /Applications/ folder
• The old XCode 3.x is installed in /Developer/ and can be independently uninstalled by running the following command :

sudo /Developer/Library/uninstall-devtools –mode=all

It is a nice mv from the XCode Apple Developers Team :)

sudo <Xcode>/Library/uninstall-devtools --mode=all

where <Xcode> is the path to the Developer folder (the one with 'Xcode 3.2.5' in it) This won't affect the 'Xcode 4.0.2' installation since it's in a completely different folder.