If you choose any tag then the tag will be displayed in the slider. If there is no tag match then sticky post will be displayed instead.
You mean that you don’t wanna add slider ? Then go to dashboard -> apperance -> customize -> ambition theme options -> featured content settings and click on check to disable slider.
I do want to use the slider and i understood how it works.
But, when i tag a page with a featured image of 1170×650 px, this image appears in the home page slider in ± 720 X 400 px (and not in full width as it is in your live preview).