This is probably incredibly obvious, but I can't seem to figure out how to do this.

So I'm using the iPad email app to read my mails. Works very well. It's configured to work with my Google apps account (same as a normal gmail account, but using my own domain). I can read the emails, send emails, forward them, archive them,... But not delete them, not as far as I can see anyway. So every time I want to delete an email now, I need to to login to Google's web application. This is annoying.
Is this really not possible, or am I overlooking the obvious here?

There's a little icon at the top right that looks like a box that puts it into the trash. On most email servers it looks like a trash can, but on my gmail it looks like a little box.

Indeed. There's no trash can icon, but this little box and arrow. And yes, the mail indeed dissapears when I tap it. But it also seems to be permanently deleted, without ending up in the trashcan first. Is this true for you as well?

I'll have to check. The other thing you can do is use the arrow pointing into the folder icon (which puts an email into a different folder) and put it into the gmail trash folder.

Ah! That's a good idea! I'll use that instead, thanks!