With the stroke of a pen, the President could (as far as I know), switch any of the FBI’s functions to another federal law enforcement agency. For example, counterintelligence and public corruption could be switched to some combination of the DEA, ATF or Secret Service. It seems to me that shutting down the FBI is unrealistic but changing up roles and missions is not.
You mean like putting the CIA in charge of muslim outreach?
asking for a friend.