LWT3

With Citi a lot of things aren't logical, so anything is possible. However, I doubt it will work. You're entitled to a refund of the annual fee if you close the account within 37 days, but when you downgrade, you're not closing your account. Instead, you carry over the history and credit limit on the account to a new product, but I think it's considered the same account.

Fwiw, the 6th comment in the link you posted says Citi won't allow downgrades on the Exec card.