include --None--

[priyasunku]

@Greg L - I dont think this is possible. you can try 'Look up select box' 

If my answer solved your issue, please mark my answer as ✅Correct & 👍Helpful

[David Whaley]

You could possibly create a record in the table your list collector is referencing with the display value of --None-- and set it as the default.  However, if this is mandatory variable you would need an onSubmit client script to check if the value is --None-- to make the user select an actual value.