(binder) Need help with a macro to unbind keys.

[Khatovar]

http://www.wowpedia.org/API_SetBinding

Looks like running the script without a command parameter is how to unbind

-- Remove all bindings from the right mouse button.
SetBinding("BUTTON2");
-- Restore the default binding for the right mouse button.
SetBinding("BUTTON2","TURNORACTION");

So /script SetBinding("SHIFT-4"); should unbind.