public KnowledgeGraphRelationshipDescription( 
   Guid origin,
   Guid destination,
   IReadOnlyDictionary<string,object> attributes
)

{
  var create_rel2 = await QueuedTask.Run(() =>
  {
    //Instantiate an operation for the Create
    var edit_op = new EditOperation()
    {
      Name = "Create a new relationship record",
      SelectNewFeatures = true
    };

    //Use datasets or feature layer(s) or standalone table(s)
    //Get a reference to the KnowledgeGraph
    //var kg = ... ; 

    //We will use a relate called 'HasEmployee' to relate an Organization w/ a Person
    //Use either tables or map members to get the rows to be related...
    var org_fc = kg.OpenDataset<FeatureClass>("Organization");
    var person_tbl = kg.OpenDataset<Table>("Person");

    //Get the relationship dataset
    //We can use either a table or standalone table
    var emp_tbl = kg.OpenDataset<Table>("HasEmployee");

    // get the origin, destination records
    Guid guidOrigin = Guid.Empty;
    Guid guidDestination = Guid.Empty;
    using (var rc = org_fc.Search())
    {
      if (rc.MoveNext())
        //Use the KnowledgeGraphPropertyInfo to avoid hardcoding...
        guidOrigin = rc.Current.GetGlobalID();
    }
    using (var rc = person_tbl.Search())
    {
      if (rc.MoveNext())
        //Use the KnowledgeGraphPropertyInfo to avoid hardcoding...
        guidDestination = rc.Current.GetGlobalID();
    }

    //Add any extra attribute information for the relation as needed
    var attribs = new Dictionary<string, object>();
    attribs["StartDate"] = new DateTimeOffset(DateTime.Now);

    var rd = new KnowledgeGraphRelationshipDescription(guidOrigin, guidDestination, attribs);
    //Add a create for the relationship to the operation
    edit_op.Create(emp_tbl, rd);

    //Do the create
    return edit_op.Execute();
  });
}

{
  var mv = MapView.Active;
  await QueuedTask.Run(() =>
  {

    var edit_op = new EditOperation()
    {
      Name = "Delete a Relationship record"
    };

    //We are  going to use mapmembers in this example
    //we could equally use feature classes/tables
    var kg_layer = mv.Map.GetLayersAsFlattenedList()?
                  .OfType<ArcGIS.Desktop.Mapping.KnowledgeGraphLayer>().First();

    //entities
    var entityOrg = kg_layer.GetStandaloneTablesAsFlattenedList()
                    .First(child_layer => child_layer.Name == "Organization");
    var entityPerson = kg_layer.GetStandaloneTablesAsFlattenedList()
                    .First(child_layer => child_layer.Name == "Person");

    //Relationship
    var rel_stbl = kg_layer.GetStandaloneTablesAsFlattenedList()
                    .First(child_layer => child_layer.Name == "HasEmployee");

    // get the origin, destination records
    Guid guidOrigin = Guid.Empty;
    Guid guidDestination = Guid.Empty;
    using (var rc = entityOrg.Search())
    {
      if (rc.MoveNext())
        //Use the KnowledgeGraphPropertyInfo to avoid hardcoding...
        guidOrigin = rc.Current.GetGlobalID();
    }
    using (var rc = entityPerson.Search())
    {
      if (rc.MoveNext())
        //Use the KnowledgeGraphPropertyInfo to avoid hardcoding...
        guidDestination = rc.Current.GetGlobalID();
    }

    var rd = new KnowledgeGraphRelationshipDescription(guidOrigin, guidDestination);
    edit_op.Delete(rel_stbl, rd);
    edit_op.Execute();//Do the delete
  });
}