Every year the system starts fresh to a certain extent. You only see stats from the year that is selected in the filter and not a combination of all years. This means at the start of the calendar year you will have a fresh account.
If you are partially through a year and want to start fresh then you can delete all the rounds played in that year.
Another option you have is to keep your rounds in your account but not have any of the round data pulled through to your 'Performance' pages and count towards your stats. This would mean although you can see these rounds from that year in your account in the background it would be like they weren't there meaning again a fresh start for stats in that year. To do this you would do the following:
1) Click the 'Edit' and then 'Edit and Sign Off' button on a round.
2) Untick the box next to 'Include this round in your performance statistics?'
3) Click the 'Sign Off' button.
This now means that your shot data and statistics from that round will not count towards your Performance data but your round is still on your account. You can at anytime reverse this by ticking that same box and clicking 'Sign Of'" to then include that the round in your stats again.