Hey there deanlapham,
Thanks for reaching out to us here, and welcome to the QuickBooks Community! QuickBooks Online is a great software to have. It can help make running your business smoother. I would be happy to point you in the right direction.
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 reach out to your QuickBooks Online accountant, if you have one. The second option would be 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. If you would like to add your QuickBooks Online accountant to your books you can do so by going to the My Accountant tab of your QuickBooks account. You can also find an accountant that has experience using QuickBooks near you by clicking on the Find a pro to help option in that section. If you would like an agent to un file for you, you can reach them by following one of these methods:
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.