You can either leave it as it is, or delete the erroneous records.
Although there is no way to edit usage records from NetWorx, you can directly edit the database:
- Download SQLiteSpy.
- Launch it and load the NetWorx database file located in %ALLUSERSPROFILE%\Application Data\SoftPerfect\NetWorx.
- Run the following query in SQLiteSpy replacing YYYY-MM-DD with the year, month and day before which you want to delete records. For example, this will delete all records prior to 2015:
DELETE FROM usage WHERE date('1899-12-30', '+' || DAY || ' days') < '2015-01-01'