code: public void clearCredential(String userId) throws AuthException {
          try {
              authorizationCodeFlow.getCredentialDataStore().delete(userId);
          } catch (IOException e) {
              throw new AuthException("Unable to clear credential.", e);
          }
      }
docs: Clears the credential for the user in the underlying (@link DateStore}.
  @throws AuthException If the credential could not be cleared.