Changing value of form in parent template

using vazco:universe-autoform-select with aldeed:autoform, I am having a tough time finding a way to clear a specific value from the form when the form is in a parent template.

My current attempt was using aldeed:template-extension to grab the parent template and then trying to set the value of the field to null, but that didnt work.

The attempt:
template.parent(1).$('#Category :selected').text() = null;