You can only delete bundles that you created/cloned. All other bundles are named after the device they are associated to.
The Bundle name works like this [Device Name]:[SketchUp Version] so for me I have RICH-ASUS:13
Find the setup you want to clone and use that as the master installer for other devices and SketchUp versions.
There is always an element of management when dealing with multiple devices and multiple SketchUp versions.
For me I've 20 bundles listed going back to SketchUp 8 on a device I don't have anymore.
We don't support device bundle deletion because the next time you start SketchUp on that device the bundle will be created again.
We'd happily listen to feedback on how to improve it though. We added this bundle feature to see what would happen. We haven't spent too much time refining it.