FYI - these Contact examples are for 0.9.3 and before.   
 Please see http://docs.phonegap.com/phonegap_contacts_contacts.md.html for 0.9.4 and beyond.


   function removeContact() {
    navigator.contacts.chooseContact(removeContact_Return, null);
}
function removeContact_Return(contact) {
    if (contact) {
        navigator.contacts.removeContact(contact.recordID, removeContact_Success, null);
    }
}
function removeContact_Success(contact) {
    if (contact) {
        navigator.notification.alert(contact.firstName + " " + contact.lastName, "Contact Removed", "Dismiss");
    }
}