Possible to delete field with Format value action?

Is it possible somehow? I tried leaving the "format string" box empty but the action couldn't be created that way (the OK button wouldn't work).

The remove fields action is there for that purpose.

I know, but I can't use IF functions in it to delete certain tags based on file type. And I'd like to be able to do what I'm trying to do with a single Action Group.

Then use %dummy% as the format string

It works! :w00t:
Thanks