It's just a report, publish, extended family report, use all individuals. If you have unattached PEOPLE they will be at the bottom left, individually or in groups. [I usually select home person to start with.] You can delete a person by selecting them in the chart right click and delete. Thee will be a confirmation so you don't do it by accident.
However if you truly do not have detached individuals but only detached sources, then your best bet is to go to the sources tab and sort by person, unlinked will be at the bottom.