I would guess you are refering to the info like :-
date posted, the post that you used and the MCX file you posted from.
This is essential info for most Co's as it adds tracability to an NC file
if after a year and a couple of part drawing revisions and you want to alter the original MCX file, this info points to it.
But, if you want to not have it posted, it requires a post edit using a normal text editor ie "Mastercam editor", "Cimcoedit", even "Notepad"
...copy your post...now
The only key you need to use is the # , as this acts as a comment on any characters after it
The area you need to find is "pheader" or "psof"
do a search for the text "sprogname"
put a # at the beginning of the line you think is unwanted, save it, post 1 operation.
do a small edit, save it, check it.-----make sure you are working on the correct area
....and just to make you nervous....these posts can control $million machines, so a little mistake can have large consequences