You can delete one or all of your transactions from an account in AccountsPrep.
How to Delete a Single Transaction
Go to Banks > Bank Reconciliation and select the bank account.
Select the relevant link to posted or unposted data.
Click the relevant batch and click Edit.
Click the small red 'x' icon next to the transaction to delete it.
The transaction is crossed out, click Delete to confirm or Restore to cancel.
How to Delete an entire batch
You can also delete all transactions from a batch.