I didn't find an answer to this when quickly looking over past discussions.

What I want to do is clear a cell value out after eight hours or so. I may
have a production line that ran yesterday but that is not running today. I
have production tabs in an Excell 2003 spreadsheet with a summary tab that
everything is totalled into. If the line doesn't run today their past data
is still in their tab. I would like the ability to automatically clear out
their production data so it doesn't get totalled in my summary page after the
date changes or after a set time period. That way when I am totalling up a
days worth of production I'm not counting a line that may not be running
today.

I hope this makes sense. Thansk!