How can you remove an extension bundle from SPSS 23, after you have installed it ? Under Utilities/Extension bundles menu, you can only view installed bundles (which is read-only) and edit(which allows only for editing the details of an extension, not removing it)
With Statistics 24, the Extensions > Extension Hub menu takes you to a display where you can click on the Installed tab and then check Uninstall extension.
In earlier versions, the removal process is manual. You can uninstall the dialog box using Utilities > Custom Dialogs > Custom Dialog Builder. Then do File > Uninstall.
If you want to also remove the implementation, you need to manually delete those files. Look at SHOW EXT to see where they might be, and then just delete the .xml, .py, and .R files on that path that have the extension name. (Or .sps and .java files if those languages were used to create the extension.) There will also be a subdirectory with the extension name that should be removed. However, in most cases it is just the menus that people want to clean up. The other files are too small to worry about.