Yes, you can.
You can decide exactly how much funds each card has at any given time.
This feature is particularly useful when you want to free up some committed funds from one card to allow payments to go through another card.
Simply select the application, scroll down to Budget details and click Edit.
In the Card balance, fill in the amount you want this card to have, and save the changes.
If you want to completely empty out a card because it holds a large amount, but the payment is not due for another 3 months, you can go to the top right of the application right above the card, and click More actions > Flush money.
All the funds in the card will be moved back to the main account and will be available to spend on other cards.