As long as a bonus is active, any withdrawal will always result in the cancellation of the bonus.
This means that the bonus funds as well as any winnings tied to the active bonus will be lost. Only the available real money balance remains and can be withdrawn.
The exact amount remaining after the bonus cancellation can be seen directly under Cashier > My Balance. There you will see how much real money is currently available.
You have two options:
Either you cancel the bonus and withdraw your available real money, or you complete the bonus requirements first. You can find the bonus terms and your current wagering progress under Cashier > Bonus History.