If you are allowed to correct a timesheet after submission, it will have a Reopen button in its top, left-hand corner.
To edit a timesheet:
You may be required to give a reason why you’re resubmitting the timesheet.
If you don’t see a Reopen button on your timesheet, but you know that the timesheet includes an error, talk to your supervisor.
You may have permission to reopen timesheets that are awaiting approval, but not ones that have already been approved.
To edit a time off booking, go to your Time Off tab. You may not have permission to edit time off that is in certain states, such as bookings that occurred in the past, or that have already been approved. If this is the case, contact your administrator.
You may be able to reopen either or both of those things, if you use a time entry workflow timesheet. Find out more on the Submitting timesheet entries ahead of timesheet submission topic.