public class ParentTable
{

    private long id;
    ...
    @OneToOne(mappedBy="Parent",cascade=CascadeType.ALL)
   @JoinColumn(name="id")
   public ChildTable getChildTable()
   {
      return childTable;
   }

   public void setChildTable(ChildTable childTable)
   {
      this.childTable=childTable;
   }
    }


public class ChildTable
{
...
   @OneToOne(targetEntity =ParetTable.class)
   @JoinColumn(name = "id", nullable = false, insertable=false, updatable=false)
public ParentTable getParentTable() {
      return parentTable;
   }

   public void setParentTable(ParentTable parentTable) {
      this.parentTable = parentTable;
   }
}

ParentTable parentTable=(parentTable)getHibernateTemplate().get(ParentTable.class, 12345);

ChildTable  childTable=parentTable.getChildTable();
getHibernateTemplate().delete(childTable);