Good question. It's bugged me also. Safest way to remove the speech would be to replace it with a silent file. There were silent files available to replace the often too frequent 'yes sir' responses. I've uploaded a silent .ogg file for you at this link, just re-name the file to whatever applies.
http://rapidshare.de/files/30581713/ALT_Silent.ogg.html
As for removing the text, that would be a bit more tricky. I can see it listed in the 'en_menu.txt' and 'gr_menu.txt' files in the data/Menu folder, but simply deleting it will mess things up as they are in a numerical sequence...And of course simply replacing the line of text with a blank line wont do either. Hopefully someone will know.