We have warned how using iPhone in-built "Erase all content and settings" option on a jailbroken phone can result in a infinite boot-loop, and also suggested the free Cydia package to tackle the issue of "erasing iPhone address book" on a jailbroken phone.

Free iTunes AppStore utility "My Contacts Backup" can not only "Backup and restore" your Apple iPhone contacts but also allows you to wipe the address book clean in a single shot.