code: public void releaseInstance(ReleaseInstanceRequest request) {
          checkNotNull(request, "request should not be null.");
          checkStringNotEmpty(request.getInstanceId(), "request instanceId should not be empty.");
          InternalRequest internalRequest = this.createRequest(
                  request, HttpMethodName.DELETE, INSTANCE_PREFIX, request.getInstanceId());
          this.invokeHttpClient(internalRequest, AbstractBceResponse.class);
      }
docs: Releasing the instance owned by the user.
  
  Only the Postpaid instance or Prepaid which is expired can be released.
  After releasing the instance,
  all of the data will be deleted.
  all of volumes attached will be detached,but the volume snapshots will be saved.
  all of snapshots created from original instance system disk will be deleted,
  all of customized images created from original instance system disk will be reserved.
  
  @param request The request containing all options for releasing the instance.