Please note: this feature is in Private Preview at the moment, which means we're still making a few tweaks here and there to make it even better. It also means that while only Early Adopter customers can get access to it right now, when it's out of Private Preview it will be available to all customers, but may be restricted to certain subscriptions.
It's easy to archive Landing Page templates that are no longer in use.
From the Marketplace, scroll down and select 'Your Pages' on the left side navigation.
On the bottom right of each template, select the ellipsis button (three dots), select 'Copy' or 'Archive'.
When prompted, select 'Yes, please' to archive the template.