Right Click on any medication header in the Summary medications field and select 'Discontinue Rx'.

Now you can choose a date upon which you want the medication listed as discontinued. The date will default with today's date. You can also add any notes to provide additional information on why the medication was discontinued. When you are finished, hit Discontinue.

When you select Discontinue Rx in the Summary, you will also place an entry in the patient's Rx History log.

Medications can also be discontinued via the Rx Manager 'Medications' display. Clicking the 'Discontinue' button to the right of a listed medication will cause the discontinue dialog to be displayed and the corresponding Rx History entry to be made.