As I fumbled with moving the hundreds of Contacts in my Outlook to my new Android phone, I discovered there’s no easy way to delete all contacts directly from the phone. From the T-mobile G1 interface, you have to manually select each contact and delete them individually, which takes a long time. The alternative, which can be a little scary, is to delete all the contacts from Gmail and wait for the phone to re-sync. If you no longer have any contacts in Gmail, you’ll also no longer have any contacts on your phone. So the solution to deleting all the contacts on your G1 is to sign in to Gmail on your PC, go to the contacts page, select all contacts and delete them.