How to sell poly on coinbase

I own poly on coinbase and just received an email from them saying we need to upgrade to polyx before 1/31/2024. At this point I would simply like to sell all of my poly but am unable to do so on coinbase. They just don't offer that option. Does anyone have any idea of the easiest way to sell poly that is currently on coinbase? I have no experience with wallets or trading crypto other than on…