How to prevent form element from sending some fields we don't want?

Remove the name attribute on the fields you do not want submitted to the server.

<form action="abc/def.aspx" method="get">
    <input type="text" />
    <input type="text" />
    <input type="text" />
    <input type="text" />
    <input type="text" />
    <input type="hidden" name="final" />
    <input type="submit" value="Send" />
</form>

This is the simplest way to achieve what you want, and it works on all major browsers.

W3 spec talks about only submitting form values when name is present: http://www.w3.org/TR/html401/interact/forms.html#h-17.2

Remove the element on submit.

On the onsubmit handler:

$(formElement).submit(function() {
    $(this.field1).remove(); //removing field 1 from query
    return true; //send
});

Disabling the form element also stops it from being entered into the query.(tested on Chrome)

$(formElement).submit(function() {
    this.field1.disabled = true;
    return true; //send
});