Running the Create Application Wizard creates an application model. This model contains basic application property values, such as the application pages and page definitions, DML processes, and multi-row operation processes. When you create a new application, you can base it on an existing application model, making the creation process more productive.
"About Application Models and User Interface Defaults" in Oracle Application Express Application Builder User's Guide
You can remove unwanted application models on the Application Models page.
To delete an application model:
Navigate to the Workspace home page.
Click the Administration icon.
On the Administration page, click Manage Service.
Under Manage Meta Data, click Application Models.
The Application Models page appears.
You can customize the appearance of the page using the Search bar at the top of the page. See "Customizing Interactive Reports" in Oracle Application Express Application Builder User's Guide.
Select the models you want to delete and click Delete Checked.