diff --git a/backend/src/main/java/core/entities/timemanager/Task.java b/backend/src/main/java/core/entities/timemanager/Task.java
index 52d38cd..41e68a9 100644
--- a/backend/src/main/java/core/entities/timemanager/Task.java
+++ b/backend/src/main/java/core/entities/timemanager/Task.java
@@ -34,7 +34,7 @@ public class Task {
     @OneToOne(mappedBy = "task", cascade = CascadeType.ALL, orphanRemoval = true)
     private TaskSerieItem taskSerieItem;
 
-    @OneToMany(mappedBy = "parent", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.EAGER)
+    @OneToMany(mappedBy = "parent", cascade = CascadeType.REMOVE, orphanRemoval = true, fetch = FetchType.EAGER)
     private Set<Task> subtasks;
 
     @ManyToOne
diff --git a/backend/src/main/java/core/entities/timemanager/TaskSerie.java b/backend/src/main/java/core/entities/timemanager/TaskSerie.java
index 87df8cd..1cf48e9 100644
--- a/backend/src/main/java/core/entities/timemanager/TaskSerie.java
+++ b/backend/src/main/java/core/entities/timemanager/TaskSerie.java
@@ -15,9 +15,6 @@ public class TaskSerie {
     @OneToMany(fetch = FetchType.EAGER, mappedBy = "taskSerie", orphanRemoval = true)
     List<TaskSerieItem> tasks = new ArrayList<>();
 
-
-
-
     public long getTaskSerieID() {
         return taskSerieID;
     }
diff --git a/backend/src/main/java/core/entities/timemanager/Taskgroup.java b/backend/src/main/java/core/entities/timemanager/Taskgroup.java
index ffea384..cc16b99 100644
--- a/backend/src/main/java/core/entities/timemanager/Taskgroup.java
+++ b/backend/src/main/java/core/entities/timemanager/Taskgroup.java
@@ -25,7 +25,7 @@ public class Taskgroup {
     @JoinColumn(name = "taskgroupuser", nullable = false)
     private User user;
 
-    @OneToMany(mappedBy = "parent", cascade = CascadeType.ALL, fetch = FetchType.EAGER, orphanRemoval = true)
+    @OneToMany(mappedBy = "parent", cascade = CascadeType.REMOVE, fetch = FetchType.EAGER, orphanRemoval = true)
     private Set<Taskgroup> children;
 
     @ManyToOne
@@ -33,7 +33,7 @@ public class Taskgroup {
     private Taskgroup parent;
 
 
-    @OneToMany(mappedBy = "taskgroup", cascade = CascadeType.ALL, fetch = FetchType.EAGER, orphanRemoval = true)
+    @OneToMany(mappedBy = "taskgroup", cascade = CascadeType.REMOVE, fetch = FetchType.EAGER, orphanRemoval = true)
     private Set<Task> tasks;
 
     public Taskgroup(String taskgroupName, User user) {
diff --git a/backend/src/main/java/core/services/TaskSeriesService.java b/backend/src/main/java/core/services/TaskSeriesService.java
index 4d99d09..fbfbf22 100644
--- a/backend/src/main/java/core/services/TaskSeriesService.java
+++ b/backend/src/main/java/core/services/TaskSeriesService.java
@@ -135,11 +135,7 @@ public class TaskSeriesService {
         task.setTaskSerieItem(null);
         taskSerieItemRepository.delete(item);
         if(taskSerie.getTasks().isEmpty()) {
-            for(TaskSerieItem taskSerieItem : taskSerie.getTasks()) {
-                taskSerieItem.setTaskSerie(null);
-            }
-            taskSerie.getTasks().clear();
-            taskSeriesRepository.delete(taskSerie);
+            taskSeriesRepository.deleteUnreferenced();
         } else if(task.getParent() == null){
             repearIndexing(taskSerie, item.getSeriesIndex());
         }