To begin, go to http://admgr.liebertpub.com. Make sure you're in the correct web property. Make sure you're in the correct web property. If you're not, change the web property.

Next, click the Ad Mgmt button in the top navigation:

Next, navigate to the advertiser you want to work on by clicking the letter that corresponds to the first letter of the advertiser's name:

Once you've found the advertiser, click the file folder icon to view campaigns:

You will see a list of existing campaigns for that advertiser. Next each one there are three buttons.

To delete a campaign, click on the trashcan icon: