You can probably call setFocusable to false, but of course you usually would want to re-enable that at some point.
But I'm not sure that there can be no focused component... except to declare all your components as non-focusable.
Simplest is to just call requestFocus on something else or nextFocus or whatever.
Very unusual for a text field, though. I don't know why you want to do this, but it seems not worth it, IMO.