Yes. As long as the funding is not complete, you can withdraw the application at any time. To do so, write to the support team or use the mailbox in your account.
Once the contracts have been created, you can withdraw from the contract free of charge within 10 days from receipt of the signed contract. After that, and at the latest after the payout, withdrawal is no longer possible. However, you can repay the loan early, see Can I repay the loan early?