You can edit httpd templates:
cp /usr/local/directadmin/data/templates/virtual_host* /usr/local/directadmin/data/templates/custom
Then edit templates in /usr/local/directadmin/data/templates/custom - comment out 
        CustomLog /var/log/httpd/domains/|DOMAIN|.log combined
and
        ErrorLog /var/log/httpd/domains/|DOMAIN|.error.log