To delete a work item type, right-click that work item type in the Navigator pane and click Delete in the shortcut menu. Alternatively, you can click the work item type to select it, and then press the Delete key on your keyboard, or click the Delete button on the toolbar, or click Delete in the Navigator menu. On the Confirm Object Delete dialog, click Yes.
If there are any dependencies associated with the work item type, the Dependencies dialog appears and informs you of this. Click Dependencies to view a list of any flows or viewers that use this work item type. You must resolve these dependencies by removing the work item type from the dependent components before you can delete it.