Thanks for visiting the Community, @accounts385.
Once you have filed your tax return, the option to remove or unfile it is currently unavailable in QuickBooks Online (QBO).
You'll need to contact our Support team. They have tools that can pull up your account in a secure environment and remove it for you. Be sure to provide your Company ID and the tax filing period you wish to unfile.
Here's how to reach them:
1, In QBO, click the Help (question mark) icon at the top right.
Select Contact Us at the bottom to connect with our live support.
For more insights about managing GST in QBO, I suggest checking out these articles:
Please let me know how it goes or if you have any other questions in the comment section below. I'll be more than willing to answer them. Have a great day!