Message: Some of the selected named colors are in use in your document

Cause

You have attempted to delete named colors
from the document which are being used.

What Can I Do?

Clicking Delete Unused deletes all the colors you have selected apart from those currently in use.

If you click Delete All, all the colors you have selected will be deleted, including the ones being used. The objects which are using these colors will have local colors
applied to them. The appearance of the document does not change.