Here are 3 ways to stop forms remember what has previosuly been entered into them, the fist way is to enter autocomplete="off" into the input you want to disable autcomplete for.
<input type="text" name="firstName" value="" autocomplete="off">
Another way is to apply autcomplete off to the form to disable autocomplete on all the forms inputs.
<form autocomplete="off">
Lastly you can disable autocomplete to all inputs using jQuery.
$(document).ready(function(){
$("input").attr("autocomplete", "off");
});