Lock or unlock a timesheet

Workflow and Resource Manager OR Jobs - View, Add and Edit Jobs 

You can specify the global timesheet settings to automatically lock timesheets by date or job stage. Alternatively, you can manually lock timesheets for an individual job. When you do this, users will NOT be able to add, edit, or delete timesheet entries for that particular job.

You can unlock a previously locked job. To do so, return to the Job Details page, then click Unlock Timesheets.