Deleting folders in the Mail app on your iPhone or iPad will delete the folder and the messages inside it. It’s one of the easiest ways to reclaim storage space on your phone and tidy up your emails. Here’s how to do it using the Mail app for iOS 13, iOS 12, and iOS 11.
How to delete folders on iPhone
After you have verified that the folder no longer contains any messages you want to keep, you can delete the folder.
Go to the main Inboxes screen.
Tap Edit. Then tap the folder you want to delete.
