Of course, ego is just an idea. Ego here means the identity of the Self. What normally identified as Self is ego. For example, I am writing this post. This I-ness is ego. This ego is false and it should be overcome. How? Of course, by identifying the true-self. How could you identify it. By self-enquiry. Who am I? Am I this body? Am I this mind? Am I anything beyond this? A sincere meditation upon the questions like these will lead you to Self-Actualisation.