Fix Select2 dropdown select fields so that empty can be selected on edit

When a select field is saved with a value, it is not possible to re-select an empty value.

This can likely be fixed with configuration on Select2:

$('select').select2({

  placeholder: 'This is my placeholder',

  allowClear: true

}); 

"allowClear" will provide an "x" icon to clear the setting for select fields.