How do I delete a suggested reference?

To delete a suggested reference move the mouse over the reference you want to delete to display the available options:

If you move the mouse over a suggested reference, the available actions you can perform will appear at the top-right corner.
If you move the mouse over a suggested reference, the available actions you can perform will appear at the top-right corner.

Select the icon of the hidden eye to discard the reference and hide it from the Document » References section at the sidebar of the post editor.