code: public Observable<OperationStatus> deleteRegexEntityModelAsync(UUID appId, String versionId, UUID regexEntityId) {
          return deleteRegexEntityModelWithServiceResponseAsync(appId, versionId, regexEntityId).map(new Func1<ServiceResponse<OperationStatus>, OperationStatus>() {
              @Override
              public OperationStatus call(ServiceResponse<OperationStatus> response) {
                  return response.body();
              }
          });
      }
docs: Deletes a regex entity model from the application.
  
  @param appId The application ID.
  @param versionId The version ID.
  @param regexEntityId The regex entity extractor ID.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the OperationStatus object