Usually you don't clear old data, you implement a way to only look at current year's data...
Agree with siplus here. Assuming you have a date field for each payout data entry, use the calculation Year (my_payout_date), number result, to group all entries by year. I have my own Filemaker bookkeeping database that started in 2000. You would be surprised how often you will want to look at some previous year's data.
If you are in the U.S.A. you need to keep a few years records for any type business, some types of businesses are required to keep some records / data longer. If you get audited by the IRS you will have to provide records.
Copy the file.
Save the old one for historical purposes.
In the new copy delete all relevant records.
ps i concur with the others that this is probably not the best strategy.