Delete the "Phone" part of a contact whilst keeping the "Google" part? HTC Hero with HTC Sense - Android 2.1.

Contacts can be either stored on "SIM", "Google" or "Phone". Many contacts are duplicated on "Phone", but I want them all in "Google" so I can manage easily. I've managed to copy all "Phone" to "Google", but now want to remove from "Phone".
However, whenever I try to delete a contact (e.g. Bob), it deletes Bob from "Phone" AND "Google". I can't find a way to delete Bob from just "Phone" - any ideas? Factory reset is throwing the baby out with the bathwater, and not a great technical solution...
To answer my own question - here's a different approach to achieve this (Google-only contacts)


Ensure all required Android contacts are synced to Google
Export the contacts to CSV on a computer
Delete all contacts from the Android (that'll be both "Phone" and "Google")
Import the contacts from CSV to Google
Google will then sync to the phone


Kind of obvious in hindsight. Hope this benefits the community in some way!