You cannot transfer a balance from your Discover credit card to a checking account. A credit card balance is a debt that you owe. A checking account balance is an asset that you own. And a credit card balance transfer is when you use a credit card to pay off an existing debt, from another credit card or loan, in order to get a reduced interest rate.
If you're talking about transferring money, you can do that with cash advances, convenience checks, money-transfer services, PayPal and via Square’s Cash App. Also, by paying a friend through Venmo or Amazon Pay, if they are Amazon merchants. They could then return the money to your chosen bank account.
Keep in mind, though, that cash advances are costly. You’d be paying a 5% (min $10) cash advance fee, plus an 24.99% (V) APR on the advance amount that kicks in immediately.