That documentation refers to an Eclipse IDE feature, and it's Eclipse documentation. This refers to the "classic update" mechanism disabled by default. To turn it on, go to Window->Preferences and enable Classic Update. This will turn on the Software Updates menu item in the Help menu. And THAT may allow you to uninstall an Eclipse plugin.
This does NOT apply to CodeWarrior-related plugins. This is pure Eclipse. Thanks for encouraging me to figure this out. 
Hope this helps.
