You could have some Javacript that runs upon form submission, or a workflow that runs in-between tasks in your process, that goes through all of those fields and clears out their values.

But note that will be a different result that the Field Rules would have caused.  With the field rules ignoring the field, it isn't populated at all, so there is a NULL value in the field, nothing in it.  But using Javascript or Workflow to empty those fields will result in the fields being populated with blank values instead of a NULL value.

Where this could be a particular problem is if you have another task later in your process that uses those fields again, and perhaps has calculations or lookups for them.  It's possible those won't work on the later task because the form doesn't see the field as empty and needing to be processed.  I can't say for sure that is what will happen, but I can say to a computer, a NULL value and an empty string or field is not the same thing.