code: public void deleteSecretKeyServerBackup()
              throws XMPPException.XMPPErrorException, SmackException.NotConnectedException, InterruptedException,
              SmackException.NoResponseException, SmackException.NotLoggedInException {
          throwIfNotAuthenticated();
          OpenPgpPubSubUtil.deleteSecretKeyNode(pepManager);
      }
docs: Delete the private {@link LeafNode} containing our secret key backup.
  
  @throws XMPPException.XMPPErrorException in case of an XMPP protocol error.
  @throws SmackException.NotConnectedException if we are not connected.
  @throws InterruptedException if the thread gets interrupted.
  @throws SmackException.NoResponseException if the server doesn't respond.
  @throws SmackException.NotLoggedInException if we are not logged in.