There are some requirements with no link to a page that are still 'ACTIVE'
We've seen a customer who has a requirement with status 'ACTIVE' and no linked page.
We'll write an upgrade task that resets the status of requirements, if there is no link to an original page.
Re-opening on 02/08/2019
Reopening in version 2.1.2, because such requirements still appear.
Will provide a button on the "DELETED" page, so space administrators can delete a requirement that doesn't belong to any page:
Fixed in version 2.2.0.