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:
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.
Delete multiple assets
Hover your cursor over the assets you want to delete and select their [Unchecked boxes].
Select the More Actions[Drop-down menu] → Delete Ads.