Related information
You cannot delete a mixin if another mixin or component inherits styles from that mixin. Mixins and components that reference the selected mixin display in the Preview with list on the right.
Update elements that reference the mixin you want to delete — the delete option is not available until you remove all references to the selected mixin.
To delete a mixin, select the mixin that you want to delete and then click Remove from skin. On the dialog that displays, click Delete.