If you want to remove an inserted photo of a card back, you can perform the following steps:
Press this button on the app bar of the game view to show the list of secondary commands. On a PC, you can use the menu of the title bar alternatively. This menu is more detailed than that of the app bar, so you can reach almost all the panes directly.
Click this button to go to next pane. Alternatively, you may press the key combination Alt+Right arrow.
Click this button to go to next pane. Alternatively, you may press the key combination Alt+Right arrow.
Click this button to remove the current insertion from the card back.