Per Wikipedia:

“As of 2018, these regulations remain in effect in the Code of Federal Regulations, Title 28, part 600 (28 CFR §600).[6] The regulations restrict the power to fire the special counsel into the hands of the attorney general alone, and they forbid the firing of the special counsel without good cause. They are internal Department of Justice regulations deriving their power from various acts of Congress, such as U.S. Code, Title 28, section 510 (28 U.S.C. 510).[20] Congress has the power to directly limit the firing of special counsels or to delegate that power to the Attorney General. An agency regulation promulgated within the authority granted by statute has the force and effect of law, is binding upon the body that issues it, and can't be arbitrarily revoked.[13]”

It’s a pretty interesting read tbh