Got me worried for a while, but I have just figured out how to do this..
Follow these steps:
> Go to your App menu (from Home screen)
> Go to People (the app)
> Click on Phonebook (top left) to choose contact sources
> Select (tick) all Google accounts (or any other sources you'd like to remove)
> Deselect (untick) anything you want to keep (e.g. SIM, Phone, Messenger)
> Tap the option button (to the right of the "add" and "search")
> Choose "Delete Contacts"
> Tap the option button again to "Select All"
> Finally, press "Delete" to remove all those contacts.
If you return to your Messaging app all those annoying Google contacts will no longer appear in the list.
I hope that helps, I signed up to the forums purely so I could post this working fix because I couldn't find one..
