Good afternoon, Ashley1981.
Thanks for turning to the Community for support. I'd like to make sure you get the support you need.
When it comes to un filing sale tax, there isn't a way to un file directly from your QuickBooks account. However, there are two options that you can chose from. The first option would be to contact your QuickBooks Online accountant if you have one. If you dont, you'll need to reach out to the support team outside of the Community as they have the necessary tools to do the un filing for you from our end.
Schedule a Callback or start a Chat: click (?)Help in the upper right > type and enter "Contact support" into the QB Assistant > click Contact Us > explain your situation > click Let's Talk > choose Get a callback or Start a Chat.
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If you have any other questions, feel free to reach out here.