If want to disable the option to capture card details for your account users, so they will not be able to select this option in the Payment tab of your bookings:
1. Go to Settings>Online payments (only the account owner can access this section of the dashboard)
2. In the Remember credit cards section, untick the Give staff the option to capture card details Checkbox 
3. Save. You will be required to input your Bookeo password to confirm the change made.