How to clear out form field info on page load

Hi I have created a landing page we are going to use at PyCon this year for people to create accounts for our product.  We are going to have this on a Ipad at our booth and pass it to people who are interested in signing up.  I was looking for a way to have no prefil text inside the form fields.  I disabled pre-fill inside the form editor and still there are forms that get preloaded with text of the last form submit.  I try using some javascript to clear out the forms but have had not luck.  The form is on a landing page that is being iframed and displayed on another landing page.  Has anyone else run into an issue similar to this and have a solution they would willing to share?  Thanks!

-John