A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data
I have been able to set zero margins but when printing is does leave a small margin as can be seen in the second screen shot.
The last custom setting that I have marked in red is due to the margin setting in Excel Page Setup as per the first screen shot because the printer does not print to the edge of the paper but it is quite close.
Note that it is necessary to set both the standard data top and bottom and right and left to zero as well as the header and footer to zero if you want to maximize the number of rows/columns that can be displayed as a single print sheet.