This is only applicable if you have set the ledger to keep archived transactions. If so, archived customer transactions are stored in a separate archive file once they have exceeded the history length on the customer's account. You will need to delete transactions from the archive file at times, to improve processing speed. Depending on disk space, you may need to perform this activity annually, quarterly or even on a monthly basis.
There are a number of options available. You can:
You must have:
Open: Sales Ledger > Utilities > File Maintenance > Purge Transactions.
Overview
Other tasks
Delete archived transactions (Purchase Ledger)
Delete archived sales and purchase orders and returns
Delete archived batch/serial history
Reference