code: public Observable<Void> deleteValueAsync(String tagName, String tagValue) {
          return deleteValueWithServiceResponseAsync(tagName, tagValue).map(new Func1<ServiceResponse<Void>, Void>() {
              @Override
              public Void call(ServiceResponse<Void> response) {
                  return response.body();
              }
          });
      }
docs: Deletes a tag value.
  
  @param tagName The name of the tag.
  @param tagValue The value of the tag to delete.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceResponse} object if successful.