Mr Obure was seeking to be a State witness instead of an accused person in the case of the killing of car dealer Kelvin Omwenga.
Justice Ngugi said Mr Obure cannot purport to instruct the Director of Public Prosecutions (DPP) on whether to charge him with the criminal offence or have him appear as a witness.
Murder suspects Chris Obure and Robert Ouko have denied involvement in the death of car dealer Kelvin Owenga.
While appearing virtually before Justice Mumbi Ngugi, the two denied killing Mr Omwenga on the night of August 21 in Kilimani, Nairobi.
