How can I “Delete All” from Inbox mail folder?
This was the only way at the time in iOS 8 - for newer iOS [possibly 13 onwards but unconfirmed], see iPhone/iPad Mail - rapid mass delete


If it is not already showing, from your Mailboxes view, select Edit &amp; check the All Trash option. This will then be added to the bottom of your Mailboxes list.  Needed later.



From All Inboxes, or your chosen Inbox, select Edit, then Mark, Mark all as read [seems to make a difference, toggle unread/read just so it gets the idea].

Then Edit, check the first item, which enables the Mark, Move &amp; Trash options.

Hold Move &amp; keeping it held, uncheck the item you just checked.

Release Move.

The Move options screen should appear.
Select Trash.

Wait until all items have been moved [the graphics seems to do it immediately, but experimentation has shown it can take a while to actually move, if there are a lot.

Return to Mailboxes, select All Trash.

Edit, Delete All, done.


Caveat... It seems that if you open any individual Mailbox after doing this, they are all returned. I think you may need to wait for the Settings &gt; Mail... &gt; [mail account] &gt; Advanced &gt; Deleted Messages, Remove... period to expire, before it becomes permanent.