It's nice to see you here in the Community. I'm here to share some information about getting rid of the PAID stamp on an invoice printout in QuickBooks Online (QBO).
Removing the PAID stamp on an invoice printout is currently unavailable in QBO. As of now, this option is only available in QuickBooks Desktop (QBDT). While this option isn't available yet, I encourage you to submit feedback. These requests and suggestions are forwarded directly to our Product Development Team for consideration in future updates.
This can be done from within your QBO account by clicking the Gear icon in the top right corner, then Feedback or by going to the following link: QuickBooks Online Feature Requests. QBO is constantly changing and evolving based largely on the suggestions and requests of users, like yourself. Please know that I'm going to submit feedback on my side as well for this feature.
Just in case you need it, you may visit these helpful articles that tackle emailing and printing invoices in QBO: