how to permanently delete email folders from ipad

Tap the Edit button at the top of the list of folders in the account, then select the folder that you want to delete and you should then go to a screen with that folder at the top, then the account that it's in and a Delete button - tap the Delete button and the folder (and all of the contens within it) will be deleted. You can't delete the 'standard' email folders i.e. Inbox, Sent, Trash, Drafts.