If you wish to stop or pause a live ad campaign, simply:
- Visit your dashboard, or click 'My dashboard'
- In the left side of that view, you'll find a green toggle next to where it reads 'Running' under 'Status'
- Just hit the toggle and you'll see the status update to 'Stopped'
And if you wish to resume that campaign, it's just a matter of hitting the toggle again back to 'Running.'