How to uninstall old Xcode beta safely

Just close non-beta Xcode first.

The above answer is correct for older versions of Xcode that install in the /Developer/ folder, but newer versions of Xcode Beta can be uninstalled by simply dragging the /Applications/Xcode-beta.app application into the Trash.

You can do the following to fix (remove xcode/xcode beta).

The item xcode can’t be moved to the Trash because some of its extensions are in use.

1. Control-click on Xcode
2. Select show package contents
3. Open folder
4. Delete plugins folder
5. Open finder window
6. Navigate to folder containing Xcode app
7. Move to trash