A bet placed with a Bonus Bet will pay out the winnings minus the Bonus Bet stake. For example, if you placed a $20 Bonus Bet at odds of $10 your winnings would be $180. This is calculated by multiplying the stake by the odds ($20x $10 = $200) and then subtracting the stake of the bet ($200 $20 = $180).
You can't withdraw bonus bets or bet credits, but you can withdraw winnings. Bet credits and bonus bets cannot be withdrawn, but they can be used to wager on other sporting markets your sportsbook has to offer. Some sportsbooks make you use your bonus funds or bet credits in one lump sum.