The customer wanted to restrict the color button list via the CKEditor as below:
config.colorButton_colors = 'EC022A, 007998';
But there is no effect when creating a Rich Text component as the same list of color buttons is provided.
The CKEditor configuration is javascript. Unfortunately, the browser caches this js.
So when you change a config like this. you have to flush the browser cache and to reload the page, after that it should be correct.