Fortunately, deleting folders is just as straight-forwardly accomplished a task in iPhone Mail as was setting them up and works both locally and with IMAP and Exchange accounts.
Delete a Folder in iPhone Mail
To delete an email folder in iPhone Mail:
- Go to the Mailboxes list of the account from which you want to delete a folder.
- Open the folder you are going to delete.
- Make sure the folder contains no emails you want to keep.
Move any messages you want to retain to a different folder, possibly one created for the occasion.
- Go back to the Mailboxes list.
- Tap Edit in the top right.
- Now tap the folder you want to remove.
- Standard folders — your inbox, say, the trash or, for some accounts, the archiving folder — cannot be deleted.
- Select Delete Mailbox.
- Tap Delete Mailbox again.
- Note that iPhone Mail will delete the folder including all its contents; the messages will not be moved to the Trash folder but disappear immediately.
- Tap Done.
(Updated October 2011)