If you have a metric that you do not wish to display, remove all the information you entered under Year by Year Results, Context notes, related programs, and target populations served. Leave your answers for type of metric and definition of success - The form will not allow you to continue without them. Then choose 'No, do not display' before clicking Save.
After saving, you will be brought to the Report your Results page. There should now be a Delete button on the metric you just saved: