Not really sure that is possible… I have never known anyone to get refunded for what they spent on the game… but if you're talking about transferring game cash to your personal bank account, that's definitely not possible!
Im guessing you are talking about the ATM/ Bank..? Go to the top of your screen where can you see how much money you have. Click it and this will take you to the ATM.. There you can deposit or withdraw money. When you deposit money 20% of the incoming fund would be taken out. & you can only withdraw money if there is money in the bank. Ofc.