At this time, changing the invoice to an estimate isn't an option. You can enter batch transactions in QuickBooks Desktop for the checks, deposits, credit card charges and credits, bill and bill credits, and invoices and credit memos.
So for now, you may need to delete the invoices created and manually enter an estimate transaction again.
To get started, make sure that the Estimates feature is turned on. Here's what you'll need to do:
Go to the Edit menu at the top, then click Preferences.
Select Jobs & Estimates in the left menu and go to the Company Preferences tab.
Choose Yes to the question "DO YOU CREATE ESTIMATES?".
Once the Estimates feature is turned on, you can now create an estimate. To complete the process, follow the below steps:
Go to the Customers menu at the top, then click Create Estimates.
On the Customer: Job drop-down, select a customer or customer job.