Hi Maciej
Thank you for your reply ,you are right i need more look into the task life cycle but in my case changing task status is not enough.
Administrator can exit the current task(human task 2 or human task 3) and restart the completed task which is human task 1 in the image.forward or delegate is not enough for this.
The image is not clear so first task is human task 1 and second task is human task 2 and third task is human task 3