code: @SuppressWarnings("WeakerAccess")
      public Request<List<UserIdentity>, ManagementException> unlink(String primaryUserId, String secondaryUserId, String secondaryProvider) {
          HttpUrl url = HttpUrl.parse(auth0.getDomainUrl()).newBuilder()
                  .addPathSegment(API_PATH)
                  .addPathSegment(V2_PATH)
                  .addPathSegment(USERS_PATH)
                  .addPathSegment(primaryUserId)
                  .addPathSegment(IDENTITIES_PATH)
                  .addPathSegment(secondaryProvider)
                  .addPathSegment(secondaryUserId)
                  .build();
  
          TypeToken<List<UserIdentity>> typeToken = new TypeToken<List<UserIdentity>>() {
          };
          return factory.DELETE(url, client, gson, typeToken, mgmtErrorBuilder);
      }
docs: Unlink a user identity calling <a href="https://auth0.com/docs/link-accounts#unlinking-accounts">'/api/v2/users/:primaryToken/identities/secondaryProvider/secondaryUserId'</a> endpoint
  Example usage:
  <pre>
  {@code
  client.unlink("{auth0 primary user id}", {auth0 secondary user id}, "{secondary provider}")
  .start(new BaseCallback<List<UserIdentity>, ManagementException>() {
  {@literal}Override
  public void onSuccess(List<UserIdentity> payload) {}
  
  {@literal}Override
  public void onFailure(ManagementException error) {}
  });
  }
  </pre>
  
  @param primaryUserId     of the primary identity to unlink
  @param secondaryUserId   of the secondary identity you wish to unlink from the main one.
  @param secondaryProvider of the secondary identity you wish to unlink from the main one.
  @return a request to start