First, i like the illustrated elements of your site, they look really good :-)
The callout section will still have the code for the button class inside the section, which is why that little tab is appearing. You'd need to hide that button using css, setting the btn class to display:none. If you've not used css before inside the framework, check out
which will explain the process and tools to use.
However, an easy option might be to use a contentbox instead of the callout section. Contentbox is a free blank container you can download from the store, it will appear as an additional drag and drop section so you can position it in the same place. You can then add your text and image content to it as html.
If you don't know html, place the text and image in a post in the correct layout, switch from visual mode to text mode so you can see the html. Copy and paste that html in to the contentbox.