If you are not in presentation view press F5 on your keyboard to start.
If you want divert your audience attention away from the slide you have visible on the screen but you don’t want to close PowerPoint. Simply press B on your keyboard for a black screen or W for a white screen. This means your audience will not be distracted when you need to talk.
To bring your slide back, press either B or W on your keyboard and your slide will re appear.