It is possible to select a color for an option in a choice, but once selected and published, you can change only change the color, but no longer clear the color.

This color is used in the PowerApps Grid when you select the color option to show and in charting if you want the defaulted colors. So if you no longer need the colors, you cannot clear it.

Putting them on white is also not an option, since you will no longer see any bars in charts.

Please add the option for 'clear' or 'transparant' .