To withdraw money from your Mercury Cash account, log in and follow these steps:
Select the Send option from the main panel.
Select the the currency you want to withdraw (USD or EUR)
Select the option Bank account. If you do not have your bank account already registered, you can do so from the plus (+) symbol, right next to the Choose one field. (Remember that you can only send USD to accounts whose holder is the same holder of the Mercury Cash account).
Set the amount you want to withdraw from your USD/EUR Wallet and click on Continue.
Verify the total amount to be paid taking into account that total amount is the sum between the amount you wish to withdraw and the service fee.
These questions may be of interest to you. How long does the withdrawal take to be available? - What are the withdrawal fees?