I was asked this question on FAB FM this week , ” How do your delete all emails at once on your iPhone”
Now the best set of instructions I found was at TapSmart
So how do you go about deleting all those emails at once.
DELETING ALL EMAILS
Go to your inbox, Tap Edit, then Mark All, and then Mark All as Read. This will then close the Edit mode.
Tap Edit again, and tap the top message in the inbox.
Press and hold the Move button with a finger.
While holding the Move button, uncheck the top message, and then release the Move button.
If you have a large number of emails in the inbox, wait a couple of seconds without touching your screen.
Wait and after a few moments, you will be taken to the move screen.
This will allow you to perform a bulk move on all of the selected emails.
You can move them to any of your folders.
So you want to delete them so move them to the ‘trash’ folder.