Who deleted Cortana?

Who deleted Cortana? During this period Atriox, the leader of The Banished and a large army of his boys manages to confront Cortana on Zeta Halo at the same time Master Chief appears with the UNSC and an AI known as The Weapon with the plan of containing Cortana and deleting her.

During this period Atriox, the leader of The Banished and a large army of his boys manages to confront Cortana on Zeta Halo at the same time Master Chief appears with the UNSC and an AI known as The Weapon with the plan of containing Cortana and deleting her.