Yes, you can cancel a scheduled pending or queued campaign through the Management tab within the application that you've scheduled your campaign with. For example, if you scheduled an email campaign you would need to access the email application to cancel it.
Under Actions, select Cancel to abort your campaign.
Note: Once a campaign is currently sending, it cannot be canceled, so make sure you are certain you want to send out your campaign. You have only a limited time to cancel it before the campaign is prepared for sending!
If your campaign is currently sending, you may contact Customer Support (1-866-323-6572, ext. 2) to try and cancel it; however, we cannot guarantee the campaign can be aborted before it has been completed.