In order to archive an asset, log into your account and navigate to Products > Settings> Assets.  The screen will contain two sections, one for active assets and one for archived-assets. Find the asset you wish to archive in the table and select Archive from the Actions menu. 

Archiving an asset prevents it from being selected as part of a product configuration. It is important to note that archived assets that are already attached to a product will continue to be associated with those products.

After you select Archive the asset will be removed from the active section and placed within the archived section of the page.

If you need an archived asset in the future you can easily reactivate it by finding the archived asset in the archived section of the page and clicking Restore. The asset will be added back into the active section and available for selection within product configuration.