Financials in respect to selling the business

When a business is sold you need to take the following into consideration.

You cannot just delete the General Legder Postings as the source modules will never reconcile back to the appropriate general ledger accounts.

Preferred Method :

Does a copy of Readysell need to be kept by yourself or does the old owner require a copy before clearing of any data? You may require a copy of readysell on a laptop so that it can be accessed or you may just require a back up of some sort.
Run a Profit & Loss appropriation role for year end up to the date of exchange of the business.
This will clear all the Income\Cost of Goods and Expense general ledger accounts to the appropriate P&L appropriation general ledger account.
You will need to consult with your accoutant about the figures in the year end journal as to what needs to be done next.
Reconcile the main assets and liability general ledger account balances and make the appropriate adjustment journal entries.

There is another way you can go about it however preferred method is the best way to go as history is kept.

Does a copy of Readysell need to be kept by yourself or does the old owner require a copy before clearing of any data? You may require a copy of readysell on a laptop so that it can be accessed or you may just require a back up of some sort.
Readysell would need to construct scripts to delete the general ledger postings and balances as at a date.
Readysell would need to run the task to refresh and recalculate all general ledger balances.
The new owner would need to insert a manual general ledger journal for the balance of the accounts that need to be kept and reconciled as at the time of exchange of the business as a starting point. Probably need to consult with your accountant.