curl -X DELETE \
https://msb.api.discovery.simpledemo.onap.org:30283/api/multicloud-starlingx/v1/${CLOUD_OWNER}/${CLOUD_REGIONID}/registry \
-H 'Accept: application/json' \
-H 'Cache-Control: no-cache' \
-H 'Content-Type: application/json' -k

could delete a cloud region, but failed to clean up the related cache entries inside multicloud plugins, e.g. esr-system-info-list remains in cache after deleting that cloud region.