Deleting an IMAP folder on an iPhone 4

Folks,

I have an iPhone 4 and my mail account is an IMAP account using the ISP servers located at www.1and1.com. My phone has a folder (grayed out) called RESTORED MAIL which was on the server but has since been deleted. It had close to 13,000 messages that had been deleted (and then restored) by the ISP . I retrieved the messages I needed from the server side, deleted most of the rest, and deleted the folder. It appears that the server is still “seeing” that folder and the messages on my phone and counting the used space against my total available space on the server. I called the ISP and they tell me that there is nothing they can do that I need to delete the folder from my phone. Unfortunately there does not seem to be a way of doing that using apple’s IOS. I can see the folder but can’t delete it. I know that in an IMAP account the server and all the devices that use the account stay synched (unlike POP3) but as there is no RESTORED MAIL folder on the server I am at a loss to understand why it’s on the phone. And vice versa. Is there a way to get the folder off the phone? Is there an APP that will enable help me delete the folder from my iPhone? Should I simply delete the mail account on the phone and start over? Any advice would be appreciated.

Thanks you.

Best