Hello

To remove the the top menu area you can add the following to the Custom CSS field of your templates parameters...

.hornavmenu, #search {

    display: none;

}

Presuming you wish to use this area on other pages of your site, you will need to create a separate template style specifically for your homepage to which you will add the above CSS. For details on creating multiple template styles please check out the following tutorial... http://www.joomla51.com/tutorials/item/creating-multiple-template-styles

You may also wish to remove your component/article area. Details for which can be found here... http://www.joomla51.com/tutorials/item/hiding-the-component-article-area-on-a-page

Ciarán