Simple Categories list

Is it possible to edit the menu item 'Simple categories layout' so that on a particular instance of this, only the subcategories are shown on the page?

I want to be able to link via the menu to the sub-categories and display this list of categories on the page with their avatars. I am using the simple categories layout but the category is showing as well as the subcategories. I also want to hide the blog menu options at the top of this page.

Attached a screenshot of this. I want to hide the section highlighted in yellow and the 'categories' title in blue and the category i'm in also in blue.

Thanks