Random and uneditable things appeared at the bottom of home page

Hi, are you referring to the single row products listed below the slider and smaller row of images?

If so, that is part of the homepage template and there isn’t any theme options to disable those particular sections. You can either create a custom page to display as your homepage and use blocks to display content how you’d like.

Or you can hide certain sections on the homepage using CSS. To hide the single row of products that you’re seeing, you can add the following into Appearance->Customize->Additional CSS

.home .storefront-product-section {
  display: none;
}