There are several ways to reset, we do advise to 1st make a backup of all your data. You will need either backup or raw access log files should you wish to rebuilt your stats, completely or partly.
To set stats to zero or actually empty Logaholics database:
Hover over your profile name at the top of the screen (version 3.+, a menu will open, select "maintenance".
In the maintance screen you will find a back up option as well as several delete options varying from deleting only a certain period of time from your stats to deleting all data including profile settings;
Delete a specific Date Range from this profile (leaves the profile settings intact)