Diagnosis
You try to delete site provider &v1& / &v2&.

System Response
Warning. Deletion of a Site Provider must be done with care.

Procedure
Delete Site type &v1& / &v2& only if you made sure that it is not inuse.
Make sure no sites of site type &v1& / &v2& still exist.
Make sure no BDoc types are still assigned to the Site Type.
Check all systems - development, test and production systems that mayalready use site &v1& / &v2&.