USD Digital (USD-D) is a stablecoin, which means that its price is tied to the price of USD: 1 USD-D = 1 USD in value, and this value ratio never changes. Despite this, it is an ERC20 token, and not a fiat currency issued by a government. For this reason, there is no way to transfer USD Digital to a bank account.
Our users who buy and sell bitcoin through our partner, Coinify (for the SEPA region), can Swap USD Digital for bitcoin and then sell that bitcoin for their regional fiat currency. You can also Swap USD Digital for any other cryptocurrency supported in the Blockchain.com Wallet.
If you want to exchange USD Digital directly for fiat currency, you will need to send your USD-D balance to another exchange that supports USD Digital (also known as PAX on third party exchanges).