Remove iframe

Hi Team,

I need a help in Gravity Form. when I check the w3c validation there is one error in Iframe. Please help me out how can I delete this Iframe so that w3c validate my website easily
Here is iframe
<iframe style='display:none;width:0px;height:0px;' src='about:blank' name='gform_ajax_frame_10' id='gform_ajax_frame_10' title='Ajax Frame'>This iframe contains the logic required to handle Ajax powered Gravity Forms.</iframe>
Thanks
Prashant Saxena