Close Task to update was an interesting feature that was used by the Project Manager to stop the selected tasks from showing up in resource task and timesheet views, therefore stopping users from recording time against those tasks. In Project Server 2013, the close task to update capability has changed, to leverage a new ‘Locked’ capability which behaves in a similar manner, basically you can choose to lock a task through PWA and once locked and published, the task will no longer show up in the Task and Timesheets views.