|re: I assume some part of a program is already at place |
What are you are seeing has nothing to do with your attendance project. It is nothing more than the defaults that are set within Excel for how dates are displayed. Try it in a new workbook and you will see the same behavior.
re: automatic deletion
Excel cannot delete the contents of another cell via a formula. A formula in one cell cannot perform an action on another cell. All they can do is display a result (or error) in the cell that the formula is entered in.
It might be possible to write some VBA code (a macro) to compare the dates for each employee, but you would need to have someone comfortable with running and maintaining VBA code.
Any macro written to do this would be heavily dependent on the layout of the spreadsheet and how data is entered. For example, I see that the entries for Tim are not in chronological order. Is there a reason for that?