I disagree that the automatic removal of empty elements is good.
We have a method that is updating a record with the value in an element (including clearing the field in the record if the element is empty), but leaves the value in the record unchanged if the element has been omitted.
For now, to test clearing the value in the record we have used the suggestion of putting ${empty} as the value on the Form which stops the element being omitted but sends an empty element as the property 'empty' does not exist.
However, I think that the Form window would be better to not only show whether an element has been omitted or not (as suggested in the previous post), but further to also allow the user to indicate whether they want the element omitted, rather than SoapUI doing this automatically.