I'm unable to deactivate an account from Online Services.

I have an Amex account which is showing as 'Activated for Online Services. QIF files I used to use to upload transactions to this account no longer work as they always have and Amex support blurbs say that you need to Deactivate and Reactivate the account for the new version of their files to work properly. But when I follow all the provided instructions - there is no option to Deactivate included in the Account options/Edit details screens. This is driving me crazy as surely there is a way to update this account.