Please read the documentation http://www.8theme.com/demo/docs/classico/index.html#footer
First, you need to disable footer demo blocks in 8Theme Options->General->Footer.
Next, you can create and edit footer in Static Block section. To enable Visual Composer editor for static block go to Visual Composer > Role Manager > Post Types > Custom > tick “static blocks”. In Static Block you can choose 4 columns for content http://prntscr.com/dwn8p3. Also, set “Static Block” widget from Footer widget in Appearance > Widgets.