How to edit or add tag colors
The tags shown when saving or modifying a file are Finder tags, not specific to Preview, etc.

Go to Finder → Preferences, then choose the Tags tab.




Click on a tag, then choose – to remove it.

Tag colours can be changed by right-clicking on a tag in the list and choosing a new colour for it.




  Drag your favourite tags to the area below to make them available for quick use in Finder menus.