I’m really late to the party on this but tonight I just found that Google finally implemented/fixed/added the ability to actually delete things from a mobile synced (Exchange/ActiveSync) Google account! This is huge. Up until now, if you configured your iOS device to use your account as an Exchange account, the only way to get Push email support, when you deleted an email it always went into your Archived mail folder. This made me nuts. Because of that, many people switched to using the GMail (IMAP) configuration for their mail accounts. It meant you lost Push mail, but delete could be configured to actually delete.
Anyway, Google quietly (and pretty obscurely) pushed out a change that allows you to now do real deletes from an account configured as an Exchange account. Apparently this happened in January. I missed the memo. Anyway, to get in on this awesome:
Go to m.google.com on your iOS device. Scroll way to the bottom (assuming you’re using a Google Apps For Your Domain account) and you should see something like this:
Tap on the “Tap to configure your domain” button, you should end up here:
Tap on the recycling Sync button, sign in, and you should see this goodness:
There it is. Enable “Delete Email As Trash” for this device. Tap it then delete with reckless abandon!