Before withdrawing your fund, you need to make sure that you've pay off your loan which can be referred to on your Dashboard. After that follow these steps to withdraw:
Go to Dashboard.
Select the asset you want to withdraw.
Input the amount you want to withdraw.
Withdraw by approving the transaction.
Note: sometimes your withdrawal may fail due to not enough funds in the pool. In this case, you need to wait still someone repay his/her debt. But please don't worry, if this happens, it also means that your deposit apy is insanely high.