def delete_key(key, allow_secret = false)
      err = GPGME::gpgme_op_delete(self, key, allow_secret ? 1 : 0)
      exc = GPGME::error_to_exception(err)
      raise exc if exc
    end
def delete_key(key, allow_secret = false)
      err = GPGME::gpgme_op_delete(self, key, allow_secret ? 1 : 0)
      exc = GPGME::error_to_exception(err)
      raise exc if exc
    end
Delete the key from the key ring.
 If allow_secret is false, only public keys are deleted,
 otherwise secret keys are deleted as well.