Who is responsible for accepting/confirming close out of a defect

The contract has been written to omit the Supervisor and pass on his duties and responsibilities to the Project Manager.
The Works Information states that the Contractor must follow his own quality management procedures.
The way of working is for the Employer to issue a fault/defect form, the Project Manager confirm’s whether this is a defect under the contract and Notifies as such. The Contractor then remedies the defect. The Project Manager would provide technical and contractual advice throughout the process until the defect is rectified.
In this situation who has the ultimate responsibility for accepting/confirming close out of the Defect. Does the responsibility rest with the Project Manager with him visiting the site and viewing the rectified Defect or can he rely on the Contractors self certification system.

Thanks