It is recommend to go inside the Policy statement and delete the controls (sn_compliance_control) then deleted the Policy statement itself.

However, if the you have many Policy statements and you do not want to do one by one then they can just delete the policy statement.
Or simply Delete the Policy statements(s) and that will trigger controls to be deleted along and canceled active attestations.

When a Policy Statement is deleted, the M2M association between Policy Statement and citation (sn_compliance_m2m_statement_citation) are deleted but the citation itself stay (sn_compliance_citation).