Just guessing so that I can be wrong. You are running the app from the Qt Creator and you have deleted the image from the project resources. If it is so, Qt Creator will recompile your app and it finds no image.
As far as the project files are concerned, the image must be in the resources folder. The image gets really embedded in your executable and you do not need to distribute the image along with your app. Test:
(1) Return the image to the resources. Recompile.
(2) Copy the executable somewhere else. Run. You should see the image.
(3) Remove the image from the resources (temporarily). Run the copy you have made in (2). You should see the image.
(4) Return the image to the project resources, it belongs there. Recompile, because meddling with the resources made your executable (in the Qt Creator) invalid.