The Color Change command is shown by a small blue circle with a C 
.
To delete an existing color, select it in the FilmStrip, or click a nearby object and use the left and right arrow keys to move to the Color Change, then click Delete. To change a color, click the color block in the color worksheet on the Design Panel, or right-click the color change in the FilmStrip and select Properties.
For full details, see Color Change and Pick Color.