H1B application withdraw

I am F-1. A resoucing firm applied H1B for me(They think that based on my background,they can help me to find a job). It is in processing. The start date is 15 Nov. They submitted application on 20 Sep. Until now, I still don't find a job, so I want to withdraw H1B application. I called processing service center. They said that I can't withdraw it, only employer can withdraw it. Is it right?

Many thanks.