Removing the fieldwitherrors div using RJS

I have a form in which one field can be validated using RJS.

If the user hits 'submit'(which is via POST) and that field is invalid
it will return
something like :
<div class='fieldwithErrors'><input name="cc[coupon]" size="30"
type="text" id="cc_coupon" value="xxxxxx" /></div>

Using AJAX the entered data could at one point become valid and then I
need to remove the 'fieldwitherrors' div(which places a red background
around the input field) with something else using RJS.

Any ideas how I could do this?