Why Is the "Opt-Out" Button Grayed Out/Not Selectable?

If the lead has an appointment scheduled in the future, the "Opt-Out" button will not be selectable.

The opt-out button can only be used if the lead is not currently scheduled for an appointment (it will be grayed out if scheduled). This button ONLY deletes currently scheduled message(s); however, the lead can still message into ALAN, and both the live chat team and business owner can still message out manually.