There is no cleaning. They are all bad. It must be eliminated — the republic has no need of a national police force.
I agree. It can’t be cleaned up. It can be scrapped and start over or retooled.
The FBI certainly does things that are needed - counter-espionage, for example.
So you break down the agency, change its name, move people from DC and send different functions to difference states/cities.
that totally changes the bureaucracy, and makes the message clear.
Congress is not in the position to “clean it out”! Congresses power resides in the power of the purse, thus defunding it is all they can do.