1st time Mac owner (mini) THRILLED to be making a switch from that virus and bug infected competitor.

I wasn't then and still am not a "techy" type of individual so my apologies in advance for some very basic questions.

I have a very basic cartoon drawing of a magician like you would see in a kids coloring book.

I colored him in using paintbrush.

Q: I want to remove all of the color so all I have left is a black and white line drawing. How does one do that?

Thanks for any help you can provide.