How can I add a "None" (null) option to a dropdown that uses inline editor on a left join table.

How can I add a "None" (null) option to a dropdown/Select that uses inline editor on a left join table. The field itself is nullable and there are instances where a user may want to go back to the null state. How can I add this option to the select list that the editor generates? I am using .Net, Datatables 1.10.18 and editor 1.9.0.

Thank you