How to uninstall an uninstalled app from the App Store?

Solution 1:

In the special case of Xcode, the App Store downloads an installer app that you use to install Xcode. Look in /Applications for "Install Xcode.app" and delete that.

When you get Xcode installed properly, if you delete the installer, the App Store won't think it's installed and won't display updates.

Solution 2:

Just throwing out some random suggestions:

• First of all, remember to empty your trash.
• Check ~/Music/iTunes and see if you can find it there. Try moving anything related to Xcode to the trash (and empty).
• See if you have /Library/Developer. Maybe you can find any uninstaller there.