By getting Nunes to cancel the hearing.
That’s the de facto answer.
As a matter of law, there are other questions. Since Yates was a government lawyer there is some debate over what aspects of attorney/ client and/or executive privilege might apply if she is testifying to Congress about what she told whom when in the administration. Especially given how the Trump administration has been mouthing off about these topics in public which can under certain circumstances destroy attorney/ client privilege.
As a political matter saying no she can’t tell the public what she told us about the Rusdian contacts with the administration looks dreadful. If they can get the hearing cancelled, they don’t have to say a word to her.