You delete artworks in the 1up drawing.
NOTE: Layers do not belong to articles but are only associated with them. That is why the layers associated with a deleted artwork do not disappear, but remain in the project as unassociated layers (unless previously associated with other articles). These layers can then be associated to existing or new articles or remain unassociated and used separately.
To delete an article
The article disappears from the list. All layers associated with it are listed below the Other Layers group.