From the Project Explorer, you can lock and unlock projects and project reports.
This can also be done from within the Project Editor.
Check out this article for more details.
When a project is locked, it cannot be edited, and when a project's reports are locked, no reports can be generated for that project.
Locking can be configured based on the Workflow Rules settings in the Control Panel.
When a project or its reports are locked, you will see the lock icon next to the project in the Project Explorer.
When you unlock a project or its reports, a prompt will be displayed if any workflow rules exist that lock projects or reports.