This article will explain the warning message received when trying to delete attendees in recurring events.

When an admin sets up a recurring events, they have the choice of having different patrons or the same for each event.  If an admin chooses to have all patrons the same for all events, warning messages will pop up to alert admin and staff of what could happen in certain circumstances.  In an instance where an admin or staff would remove an attendees information from a recurring event, a warning message will show up to alert the admin or staff that the information is linked to every event.  Since the event has the same registration for each event in the series, deleting one can cause the others to be deleted.  As it is only a warning, you can still proceed in the deletion, however, the program is set up to notify you of the issue.