Thanks for raising this to us, @taita-ngetich.
You can try to delete the invoice, and rename the estimate to the project then convert again to an invoice.
This way, you will not encounter any prompt or messages.
For your future reference, let me share this article about customizing forms to look them more personalized: Customize your invoices, estimates, and sales receipts in QuickBooks Online.
I’ll be around to help if you need anything.