Making Radio option checked

I have a radio option that has the , where do I access this class to change the radio option that is currently checked to another option?

If I am understanding correctly, you want to change the selected value?
If so just have the other value selected (Set) already in the model.

If possible I would like to have no radio options selected on page load and let user select but currently it seems to be random on how it selects radio’s option.

If there model is empty then no button will be selected.
IF there is something in the model (Default or placed in from a hook ) then that value will be selected