Welcome to the Community, @YFC. Allow me to share additional information about deleting transactions after exporting and importing transactions from the old company file to the new one in QuickBooks Desktop.

I appreciate you following the steps provided by my colleagues above. Since you can still see the transactions and you want to delete them, you can delete them manually and one by one.

Here's how:

1. Go to Lists from the top menu bar.
2. Choose Chart of Accounts.
3. Select the appropriate bank account.
4. Locate each transaction, then right-click.
5. Click Delete.
6. Press OK in the confirmation window.

You can also check this article for the steps to delete transactions in QuickBooks Online: Void or delete transactions in QuickBooks Online.

I'd recommend making a backup copy of your company file first so you can restore it in the event of data loss.

If you need anything else about deleting transactions, you can comment below. I'm always here to help.