Once you have expired an asset and notified your partners of its impending deletion, you can delete the asset to prevent any further use of the ad/asset code. To delete an asset:
In the left navigation bar, select
[Engage] → Content → Ads.
Hover your cursor over the asset you want to delete and select the
[Unchecked box].
Select the More Actions
[Drop-down menu] → Delete Ads.
Read the pop-up notification and select OK.