Welcome. You can withdrawal funds to an unconfirmed bank account but I would not recommend it. The reason is that when you confirm your bank we have verified that you have entered the correct account and routing number information and therefore feel confident your money will make it to your bank without incident.
Although our system will allow you to withdrawal funds to an unconfirmed bank, if you have entered the wrong information your funds will not make it to the bank and will most likely be returned to your PayPal account. This results in a delay for you to have access to your money. In a worst case scenario, if you enter a wrong number, but it just happens to be a correct account number for someone else, your money may be credited to another customers bank account which makes it very difficult to get back.