Morning Eyeman,
In your project, an easy way would be to copy your 'search' button, rename it 'clear' and then in the tablegrid layout for the 'clear' button, simply remove the footer 'sum' instruction (remember that each search button has its own discrete layout and the 'clear' button is simply another search!).
Obviously, you'll still need your existing bit of script to clear all your search fields.
Please have a look at the attached. In this example, when I do a 'search' I change the layout to be 'Country, Name' with a footer count. When I do a 'clear' I change the layout to be 'Name, Country' with no footer count.
Hope this helps,
Derek.