My invoices are showing 2 ABN including the correct and incorrect one and I couldnt delete the incorrect one for some reasons

These are some ways how to delete the incorrect ABN, jullia-tr.

We can start by editing the ABN with the correct one from the company settings.

Here's how:

1. Click on the Gear icon.
2. Select Account and Settings.
3. In the Company section, edit the ABN.
4. Click on Save.

Then, let's customize the sales form to show the correct ABN. 

1. From the Gear icon, select Custom Form Styles.
2. Click on the Edit link for the invoice template.
3. In the Content tab, click on the header.
4. Make sure the ABN box is checked with the correct number.
5. Click on Done.  

In case you are using a custom template for your invoices, we can't edit the company information within QuickBooks Online. However, you can do it from the original DOCX file, then import it back. Once done, use this custom form to your invoices. 

We are always on your back to help get your account information corrected. Let us know if you need anything else.