If you've created a Design Review Issue (DRI) that needs to be deleted or retired, you can do so by going to the Document Preview.
1. Go to Issues tab.
2. For each Issue there is a delete (bin) icon shown.
3. Click on it.
4. Then click on Yes to delete.
In iTWO cx delete refers to retire. Nothing is permanently deleted. You can always find your retired "deleted" documents in iTWO cx.