I'm here to guide you on what are the actions that you need to take so you can delete the return that you've filed.
At this time, the option to delete a filed VAT form isn't available in QBO. To get this done, I'd recommend contacting our Customer Care Team. They can create a VAT unfiling request to successfully delete the incorrect VAT form.
To contact them:
Click on Help at the top menu bar.
Select on the Contact Us button.
Enter a brief description of the issue in the What can we help you with? box.
Press on Let's talk.
Select on Geta callback.
Key in your contact details, then tap on Confirm my call.
In the meantime, I'm also adding this article to guide you further in managing your taxes in QBO: Tax for QuickBooks Online. It contains topics about filing and paying tax, applying sales tax to transactions, and managing VAT rates to name a few.
I'm always here to help if you need more help with VAT or with QBO. Take care!