On the Search Workbench tab, select Topic Sets from the Show menu.
Click the delete icon (
) for that topic set.
Click OK to confirm the deletion. The dialog alerts you if there are search projects that use the topic set being deleted.
To delete a single topic:
On the Search Workbench tab, select Topic Sets from the Show menu.
In the Topic Sets menu, select Topic Sets > Your Topic Set.
Right-click the topic, and select Delete from the menu.
Click Delete to confirm.