I've created two boarding passes in Passbook using the Easyjet airline app. My question is: Can I delete the app now that the passes are in Passbook? Or will deleting the app remove the passes from Passbook?
Deleting the app will not delete the Passbook, they are independent things.
Is the same thing that an app that create entries in you calendar, when you delete it, it won't delete the calendar entries.