The only person who can fire Mueller says:
He's Satisfied With Special Counsel Mueller's Work
https://www.nbcwashington.com/investigations/Rod-Rosenstein-Says-Hes-Satisfied-With-Muellers-Work-462325583.html
When the News4 I-Team asked Deputy U.S. Attorney General Rod Rosenstein if he was satisfied with the work thus far of the U.S. Office of the Special Counsel, Rosenstein said yes.
President Donald Trump has repeatedly called the Russia probe a politically motivated "witchhunt." Only Rosenstein would have the authority to fire Mueller.
Rosenstein, a longtime former U.S. attorney in Maryland, told the I-Team in an interview Monday that he was limited in explaining why he was satisfied with the special counsels work.
When we conduct criminal investigations -- just as was true in Maryland - we dont talk about the investigation while its ongoing," he said. "So what the American people will see is only if and when a case is charged. And there are several cases that have been charged to date.