Kelly theme promo graphics

Kelly is the first theme I have prepared for ThemeForest. I've designed these graphics in Sketch. The first is the WordPress theme preview image. The second is the thumbnail for ThemeForest.

You can probably tell I have no idea how to use Sketch, but I like it anyway. Does anyone know how to delete everything outside the artboard boundaries? I can't find an easy way to do this.

keyboard shortcuts: L or F like Z toggle zoom post comment