Editing the Footer Template
Navigate to Templates > Theme Builder > click the "Footer" tab > Mosaic | Footer > click "Edit with Elementor."
The header here is simply a nav menu, the same type of element as the top. While you can create a different menu, you can also remove this and insert other contents such as a copyright or other text to be shown at the bottom of your pages.
Being a styled addition for desktop, this menu does not show a second time at the bottom of mobile/tablet devices. This setting is found in the advanced > responsive section and can be used to hide any number of other elements from showing on mobile.