Yep,
For 4.0, go into the system tab/configuration/system properties/ and edit "System.monitoring.recordLimitDays". Change it to 0, submit, and then back to default (or what you originally have it set to) and submit.
For 4.1, go into Configure/system properties/ and edit "System.monitoring.recordLimitDays" and set to 0, submit, and then back to default and submit.
After either of those steps, you should have a fresh start with all your stats, however they will be gone, so you might want to save some of your reports or screen shots if you wish to see them later.
Hope that helps,
Dan