Funds added to your wallet cannot be refunded to your credit or debit card in line with the PlayStation Store Cancellation Policy.
If other people can access Account Management or PlayStation Store through your master account on any device they may be able to use your payment methods to top up the wallet attached to it.
If you think that your account is not secure, or if someone else has your PlayStation system for any reason (for example you have sent it away for service or it has been stolen), we recommend deleting your payment details and changing your account password.
Payment details are attached to the account, not the device, so removing them on one device will remove them from your account on all devices.
Go to Account Management > [Billing Information] through web browser or go to Account Information/Transaction Management on your PlayStation system to delete your details.
If you would like step by step instructions, select the device you will be using to delete your card details: