Unenrol a site from a proposition.

Withdraws the site from the proposition and prevents further scheduling. Does not delete the site or its assets.

Use when the user is opting out of this proposition specifically — for example, they toggled it off in your app. The site and assets are kept, any other propositions they're enrolled in (such as Capacity Market) are unaffected, and the user can re-enrol later and still access their payments.

If the user is leaving entirely (moving house, support-led removal, etc.), use offboard-site-and-assets instead.

Idempotent: if the site is already unenrolled, returns already_unenrolled without making changes.

{
  "site_id": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
  "status": "unenrolled"
}