Learning Plan Added User Message

Summary

Message set up to copy the user's supervisor - how do we remove 1 supervisor from being copied on the message

Content

All,

We have a learning plan set up that includes the "Learning Plan Added User Message'. We have the user's supervisor option enabled as we want the user's supervisor to be copied when the user receive's the message. However, how do we disable 1 supervisor from being copied on this message? I see the option to +Select Users to Include/Delete but it seems that the functionality can only be enabled if there is something checked in the Add'l Users section but the options available don't show how to delete a supervisor from being copied. See attached. Any suggestions?