How to add display:none in downloaded excel file in php?

I want to manually hide some td column in downloaded excel file.
here is my code

<th align="center" style="color:black;display:none;">Bitumen(kg/min)</th> 

But when i download my excel file which contain this table column it displays. it does not hide although i write none.

removing the th with js/jQ

then use the headers

header("Content-type:text/html; charset=utf-8");
header("Content-type: application/octet-stream");
header("Content-Disposition: attachment; filename=Report($dow_time).xls");
header("Pragma: no-cache");
header("Expires: 0");