To cancel your campaign:
Log into your account with your email and password.
From the campaign dashboard search for the campaign you wish to cancel.
Once located click into the campaign.
Click the green "Live" button and then click "Pause" and confirm the change.
Once campaign changes to orange "Pause" click onto "Pause" and then select "Cancel" and confirm once again.
Your campaign will then be highlighted in red "Cancelled"
If your campaign did not deliver any impressions you will get a full refund. If your campaign partially delivered impressions then you will receive a partial refund with a credit note detailing the breakdown.