Create a feature wich enables just finished project managers see history tickets. To implement this, it is important to create project status (in special finished). When a project is marked like finished, it isn't possible to include more tickets and this project isn't visible to the others project participants, it is visible just to all project managers.
Updated by Benjamin Baroukh over 14 years ago
I suppose the easiest solution to achieve what you described is just to remove all members from the project except the project manager. In this case he, and only him, will have the full control of the project. You need to make sure that non members cannot enter issues.