Hi Mario,
As per the screenshot, it seems you are interested in keeping the image icon of your choice without any button background color.
To do that, please set “transparent” as the value for the “button background color”. Click the color picker and type “transparent” and save the settings.
Please note that since button background is transparent, the close icon will use the same background. So you might need to use custom close icon with a background color to overcome this.
Hope this helps!
Thanks,
Aakash