Currently there is no way to clear the selected value of a choice single without the use of a rule. This is a pain because users often just want to be able to deselect an option in a dropdown at a particular point in time without having to check a box or anything to trigger a rule.
Thank you very much for posting your feedback for our review. At this time, we will not be adding this request to the near-term backlog, as we are focused on other highly requested features with more votes. However, we reevaluate requests every quarter and will reach out if priorities change. Please keep the feedback coming—it is critical for our longer-term planning.