The federal reserve exists at the pleasure of Congress, and Congress can abolish the fed if it chooses to.
That's the theory.
In practice, there's always this aspect to consider (attributed to a Rothschild familly member in the 19th century):
"Permit me to issue and control the money of a nation, and I care not who makes its laws"
https://www.amazon.com/Creature-Jekyll-Island-Federal-Reserv...