I'm goinng to give this a shot...please note that this procedure will delete all types of events, not just the one's you are referencing. This means you won't be able to go back and review historical capacity reports, volume info, etc. This is a brute force method to deleting all events. Please proceed with caution.
There are specific tables in the DFM database that contain information about the events that take place.
You could in theory change this setting to be something like one day. Use the dfm option set command (dfm option set help).Then DFM will go through and purge all of the events. You could keep track by reviewing the event file mentioned above. Keep in mind this will delete all events and could create CPU overhead. I would only reccomend doing this if you really dont need any of the DFM data. In most examples people need their data so this won't work. I'm responding to mention that it can be done, though it may be brutal.
I'm just thinking outside of the box on this one. I'm not aware of any way to delete specific events, just all of them. Please proceed with caution and be sure to change the setting back once you are done.