To remove current banking details
Go to your KaChing app. Scroll down to Credit Card then select "Manage". You should now be able to remove your current card details by selecting "Remove card"
To add new banking details
To add a new card, on your KaChing app scroll down to "Settings". At the bottom of the page find the toolbar with the "Cards" icon on it. Select the "Cards" icon on the toolbar. You should now be able to add a cad to your KaChing account.