Durham was appointed Special Counsel by AG Barr in October 2020. It is not possible for AG Garland to fire Durham without a very good reason:
The Special Counsel may be disciplined or removed from office only by the personal action of the Attorney General. The Attorney General may remove a Special Counsel for misconduct, dereliction of duty, incapacity, conflict of interest, or for other good cause, including violation of Departmental policies.
Durham was appointed Special Counsel by AG Barr in October 2020. It is not possible for AG Garland to fire Durham without a very good reason: