If the header is not placed there by code, you should be able to just select the
sheet and View>Headers and Footers.
Delete the header and save the workbook.
If you want them gone from all sheets in the workbook, select all sheets before
View>Headers and Footers step.
If you are talking about deleting something from the Excel default built-in list
of headers, very little can be done.
You can change Author name in File>Properties
Gord Dibben MS Excel MVP