Sharepoint - Need to remove 'New!' icon for new items added in Document Library

If i'm not mistaken is per Site Collection only that you configure (or disable) the New Icon (set it to 0 to remove it completely).

stsadm -o setproperty -pn days-to-show-new-icon -pv Number_Of_Days -url http://sp-webApp

On the other hand you could easily replace its functionality in the web parts where you really need it with simple XSLT tricks.

To simply hide the actual icon in selected web parts use CSS

.ms-vb img { display: none; }