"To reset the dropdown to have no option selected, set the selectedIndex property to undefined ', and " Default Value-1. "
It's written here
To reset #dropdown3 I used the code.
However, there is an error with this code
"Wix code SDK error: The value of selectedIndex parameter that is passed to the selectedIndex method cannot be set to the value "-1". It must be between 0..."
Who knows how to reset the dropdown?