Here’s a bit more information about what these files do: Banner ad file optimization
You can remove the PIE.htc if you don’t plan on supporting IE6-8 (or you don’t have transparent PNGs). You may run into issues when deleting ‘Browser Detection’ since we show certain animations for certain browsers using browser prefixes.
I recommend testing on all browser you’d like to support to make sure your ad looks good. We’ll definitely look into exporting specific packages for Adform. Thanks!