Sometimes users reduce the height or width of elements up to such extent or reduce padding up to some extent that element does not remain visible due to which we can not select\edit that element email builder for all such scenarios we have a feature to view the complete element tree of your template. 

Manage Template: You will see a burger menu at bottom of the Content tab of the email builder as shown below fig once you click on that menu, it will open a Layer section.

You can click on the plus icon to view all child elements within that section

It will automatically scroll to an element in the email builder when you hover on an element in Tree

If the height of the top image is reduced up to 1O px it will not be visible in the email builder

Now, you can reach that image through Manage Template Menu, just hover the first image in the first section.