code: public void deleteFace(String faceListId, UUID persistedFaceId) {
          deleteFaceWithServiceResponseAsync(faceListId, persistedFaceId).toBlocking().single().body();
      }
docs: Delete an existing face from a face list (given by a persisitedFaceId and a faceListId). Persisted image related to the face will also be deleted.
  
  @param faceListId Id referencing a particular face list.
  @param persistedFaceId Id referencing a particular persistedFaceId of an existing face.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws APIErrorException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent