se agrego borrado en cascada para la entidad Service Port

src/FTTHBundle/Entity/ONU.php

@@ -166,7 +166,7 @@ class ONU implements DeviceInterface, TenancyIdTraitInterface, LocationInterface
     private $position = 0;
 
     /**
-     * @ORM\OneToMany(targetEntity="\FTTHBundle\Entity\ServicePort", mappedBy="onu", cascade={"persist"})
+     * @ORM\OneToMany(targetEntity="\FTTHBundle\Entity\ServicePort", mappedBy="onu", orphanRemoval=true)
      * @JMS\MaxDepth(1)
      */
     protected $service_port;

src/FTTHBundle/Entity/ServicePort.php

@@ -66,7 +66,8 @@ class ServicePort{
     private $type;
 
     /**
-     * @ORM\ManyToOne(targetEntity="\FTTHBundle\Entity\ONU", fetch="EXTRA_LAZY", cascade={"persist"})
+     * @ORM\ManyToOne(targetEntity="\FTTHBundle\Entity\ONU", fetch="EXTRA_LAZY", cascade={"persist", "remove"})
+     * @ORM\JoinColumn(name="onu_id", referencedColumnName="id", onDelete="CASCADE")
      * @JMS\MaxDepth(1)
      */
     protected $onu;