Permanently removes a DocumentTemplate, on the e-signature provider as well as in Wingspan. A template owned by another account is 404, not 403.

Refused with 409 once any signature request has been opened against the template, signed or not: the request records which template was signed, and the provider-side delete cannot be undone. Archive the template instead — PATCH with status: Inactive.

There is no requirement-definition guard: a definition may point at a template that no longer exists, and an expanded definition read simply omits the dataSource key in that case.