fixed issue with cycling from tracking types and respawning playback prefab

Assets/BodyRecording/Scenes/BodyRecording.unity

   m_RaycastManager: {fileID: 1335839538}
   m_HumanBodyManager: {fileID: 1335839540}
   m_PlaceObjectsOnPlane: {fileID: 1335839539}
-  m_UIManager: {fileID: 0}
+  m_UIManager: {fileID: 5977163237366113875}
 --- !u!114 &970751607
 MonoBehaviour:
   m_ObjectHideFlags: 0
       objectReference: {fileID: 0}
     m_RemovedComponents: []
   m_SourcePrefab: {fileID: 100100000, guid: 29251f2f7c5044cce8e7eb862b4d93ef, type: 3}
+--- !u!114 &5977163237366113875 stripped
+MonoBehaviour:
+  m_CorrespondingSourceObject: {fileID: 5977163238016480458, guid: 29251f2f7c5044cce8e7eb862b4d93ef,
+    type: 3}
+  m_PrefabInstance: {fileID: 5977163237366113874}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 0}
+  m_Enabled: 1
+  m_EditorHideFlags: 0
+  m_Script: {fileID: 11500000, guid: 162766bc881294f4b867bd32e1ef2fbe, type: 3}
+  m_Name: 
+  m_EditorClassIdentifier: 
 --- !u!223 &9004671822775026575
 Canvas:
   m_ObjectHideFlags: 0

Assets/BodyRecording/Scripts/TrackingManager.cs

             m_HumanBodyManager.enabled = true;
             m_TrackingState = CurrentTrackingState.BodyTracking;
             
-            //TODO destroy placed object
+            // destroy object that was placed in the scene
+            if (FindObjectOfType<JointHandler>())
+            {
+                Destroy(FindObjectOfType<JointHandler>().gameObject);
+            }
         }
         else
         {
                     m_UIManager.AddToQueue(new UXHandle(UIManager.InstructionUI.CrossPlatformFindAPlane, UIManager.InstructionGoals.FoundAPlane));
                     m_UIManager.AddToQueue(new UXHandle(UIManager.InstructionUI.TapToPlace, UIManager.InstructionGoals.PlacedAnObject));
                 }
-                
-                
                 m_FirstWorldTracking = false;
             }
         }

Assets/UX/Scripts/PlaceObjectsOnPlane.cs

         m_RaycastManager = GetComponent<ARRaycastManager>();
     }
 
+    void OnDisable()
+    {
+        // reset objects when component is disabled
+        m_NumberOfPlacedObjects = 0;
+    }
+
     void Update()
     {
         if (Input.touchCount > 0)