Click the "Try it" button to set autocomplete in the search field to "off".
Note: If you are new to the autocomplete attribute, fill in some text in the search field and submit the form, then reload the page, start to fill in the same values in the search field again - and see how autocomplete works. Then, click the "Try it" button to set autocomplete to "off" - if you type something in the search field now, the browser will not suggest values based on values that you have entered before.