Actually it's more complicated than that and it's why Trump is trying to do what he doing.
The Director of the Consumer Protection Bureau is allowed to appoint their own Assistant Director which does NOT require Senate approval, who will be the acting director if the director resigns, until a new director is appointed, which does requires Senate approval.
What Trump want's to do is appoint Mulveny to the post of ASSISTANT Director, who will then be able to act as the Director. Trump has NO intentions whatsoever of appointing a permanent Director because he knows that a Senate confirmation hearing would be a nightmare. So this way he gets to put someone into that job who will dismantle the bureau without any interference from Congress.
This is just anther example of how Trump wants to run the government with as little oversight as possible from Congress and the people. It's also just another example of how Trump has no respect for the Constitution nor for the laws passed by Congress. I suspect that we will see this mentioned again someday as one of the 'articles of impeachment'