Is there a way to remove the Paid status on an unsent invoice?

Hi there, 

Thanks for joining us here. QuickBooks is great program for managing your payments and keeping your books organized. I'll be glad to give you a hand and steer you in the right direction.

In order to mark an invoice as unpaid again, you'll have to delete the payment on the invoice. To do this, open the invoice in question and click on where it says "1 payment made" at the top right to see the payment. From here you can delete the payment so it's not attached to the invoice. 

There you go! You now know how to mark an invoice as unpaid again. Feel free to ask other questions by leaving a comment below. I'm here to assist.