How do I remove the outbox folder from this list?

[AC Question]

I have hotmail set up on my iphone but the menu layout is different from the menu layout i have when i log in from a computer and i would like it to be the same. I am trying to remove the outbox folder from the phone menu but when i click edit, delete mailbox, i get this message: "the mailbox could not be deleted on the server".

is there a way to hide this folder or remove it? please assist, thanks