Add support DELETE API for metadef resource types

Currently, the non existing metadef resource types are getting newly created while associating with namespace and the new
 entries gets added in 'metadef_resource_types' and 'metadef_namespace_resource_types' tables.
    But after namespace deassociation only entries from 'metadef_namespace_resource_types' tables gets deleted and 'metadef_resource_types' entries remains as it is which uneccessarily increases the size of table and there is no provision to
delete those resource types.

 To maintain the consistency, the new DELETE APIs needs to be added for metadef resource types.