How do get rid of old timesheets for old employees

I've got a bunch (700) or so time sheets for ex-employees that never got submitted. We've been really lazy about that and wanting to get better about closing out timesheets. What's the easiest way to close out those time sheets when the employee doesn't exist anymore. From approvals you can only send email reminders. I can click into the time sheet and submit but I'd sure hate to do that 700 times.