public void Delete( 
   MapMember relationshipMapMember,
   KnowledgeGraphRelationshipDescription relationshipDescription
)

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
});