Yes, you would set the choice bar to required to get all 5 slots, but if a user selects a choice and then clicks on ‘Clear Selection’, it would clear the underlying value, or you could set it to some other value that would not be in the list of choices, and the choice would not have anything selected.
Yes with 10 choice bars, this may be overkill to have 10 clears as well.
This leads me to a question. Are you trying to do this in a form or on a details screen? A form might be tricky since it activates or deactivates the submit button. Personally, I would create a custom form as they give you a lot more control and something like this would work a little better. In a custom form you could definitely even create a single button that clears all 10 of the choices at once.
Either way is probably not ideal for you, but figured I’d offer the suggestion if it helps.