@suemacaluso, while there is a way to close the old accounts in bulk, we need to understand the consequences of deleting the users from the community.
The platform anonymizes their old posts, so it isn't clear who posted them anymore, which can be jarring to other users who still use the platform. In addition to this, it could also affect Kudos, Accepted Solutions of superusers who might have helped the old users in past.
As @StanGromer mentioned, it is not possible to delete the users fully as there is a soft-delete window that defaults to 10 days. After an account is closed, it is not permanently deleted and can be restored, but will not show up in API results when searching for deleted users until the account is permanently deleted. After the soft-delete window has passed, the account is permanently deleted and cannot be restored. Support can change the default if needed.
You can view the documentation here
