Hello sir, how can I delete or undo vat once I marked filed

Hello there, @dominancee.

Allow me to provide some information on how you can undo the VAT return that was marked as filed in QuickBooks Online.

Once you have filed your tax return, QuickBooks tracks this as Mark as filed. To undo the filing, you'll need to contact our Customer Care Team and provide the following information:

• QuickBooks Online Company ID.
• The tax filing period that you wish to undo.

This team will be able to check your account and do the process for you. You can reach them by selecting the Help (?) option at the top, then select on Contact us.

Lastly, I've got here some resources that give you more details about filing VAT and removing its rate in the system:

• Remove a VAT or GST rate
• File and pay Tax/GST

Know that you can always visit me here if you have any other concerns. I'll be right here to assist you. Take care!