I changed my BankAmericard to Travel Rewards a few years back. Yes, as long as it's not a cobranded (like Alaskan Airlines, Spirit Airlines, etc.) card you can do product changes. Sometimes it might be tricky to find a CSR that knows how to do it, but most people have had good luck lately. Unlike some other lenders, it can be a slow process with BoA (usually about a month give or take a week or so).*
*Edit: By that timeline, I mean the time to receive your new card. It does change in your online account a little earlier, and as far as I know no one has actually stayed on the phone with a CSR at Bank of America for an entire month.
