By default in Gmail accounts setup through Exchange on the iPhone, any email deleted through the iOS Mail app will be archived in the “All Mail” folder of the account. When I delete an email, I would prefer that it move to the “Trash” folder so that I can easily empty it of any items that I don’t need to see ever again. It has been a small nuisance for the past few years, but luckily Google has now added an option to make this possible.
Navigate to http://m.google.com/sync on your mobile browser
Login to your account
Select your iPhone from the list of devices
Tap the checkbox to enable "Delete Email As Trash" for this device
Tap the Save button
Once this is enabled, pressing delete in the iOS Mail app will delete that email and send it to the “Trash” folder. Thank you from all those you like to keep their mail folders neat and clean!