How to clear checkboxes and set one checkbox in JIRA postfunction using Groovy with Adapatvist ScriptRunner

I have a Groovy script Post-Function using Adapatvist scriptRunner that creates sub tasks based on what checkboxes are checked on the parent issue during creation.

How do I clear all of those check boxes from the parent issue in a Post-Function and set the parent's checkbox selection to just one (different) check?