Try to add the following code to your .htaccess file and see if you get the desired result. I have not tested these codes on my server.
#Unset header cookie for static files<FilesMatch "\.(js|css|jpg|png|jpeg|gif|xml|json|txt|pdf|mov|avi|otf|woff|ico|swf)$"><ifModule mod_headers.c>RequestHeader unset CookieHeader unset CookieHeader unset Set-CookieHeader unset PragmaHeader unset ETagFileETag None</ifModule></FilesMatch>
#Unset header cookie for static files
<FilesMatch "\.(js|css|jpg|png|jpeg|gif|xml|json|txt|pdf|mov|avi|otf|woff|ico|swf)$">
<ifModule mod_headers.c>
RequestHeader unset Cookie
Header unset Cookie
Header unset Set-Cookie
Header unset Pragma
Header unset ETag
FileETag None
</ifModule>
</FilesMatch>