To redefine an existing cell or range name in the Define Name dialog box, first select the name in the Names In Workbook list and then edit the cell or range reference in the Refers To box. You can either type a new reference or select a new cell or range directly in the worksheet while the Define Name dialog box is open.

To delete a name in the Define Name dialog box, select the name from the Names In Workbook list and then click Delete. Keep in mind that when you delete a name, any formula in the worksheet that refers to that name returns the error value #NAME?