Clearing Graphs/Stats

I don't believe that is possible via the GUI and I do not know if it can be done from the command line either. There is no mention of it in the Administrator Guide version 9.4.3. You might try seeing if a custom filter will work. Click on "Edit Filter", Use the drop down box under "Time Period" and select Custom. Then you can define your custom time period. That would allow you to at least narrow down your field of results.