There is no automated way to remove "old" rows: you need to set an ExpiryDate column when you INSERT or UPDATE the row, and either check the expiry when you SELECT them, or run a regular task in your app to remove expired rows.
Me? I'd probably do expiry checks and not actually delete the rows, as I don't like discarding information. That's relatively simple: just add to your SeLECT command WHERE clause:
SELECT ... WHERE ExpiryDate >= Now() AND ...