Reauthentication is fine.
If you reauthenticate (or need to reconnect) a social profile that was already in your CoSchedule account, you will not harm or affect any messages you might have scheduled to be published to that account. LinkedIn accounts frequently require reauthentication.
If you go to Settings > Social Profiles, social accounts that need reauthentication will show an orange RE-AUTH button in the connected list.
Deleting is less fine.
If you delete a social profile and remove it from CoSchedule, you will also delete any scheduled messages associated with that account.