I had PTSD from hearing gunshots near me (now cured) yet I get frightened when hearing sudden loud bangs, how do I get rid of this fear?

Still PTSD? One of the criteria for a PTSD diagnosis is overreactivity to an event similar to the original trauma. If you are having fearful reactions to loud noises, it may mean that you should go back to your treating therapist and explore this difficulty and determine if further treatment is needed.
PTSD. In my opinion, PTSD is rarely, if ever actually cured. PTSD is all about effective management instead, involving medication as needed, and psychotherapy.
Therapy revisited. It's wonderful that you have gotten better. PTSD is often a chronic condition with symptoms that can wax and wane over time . What you are describing is an exaggerated startle response, which is quite understandable given your experience. As pointed out already, a qualified trauma therapist can assist you to foster a greater sense of safety and to desensitize you to distressing loud sounds. Best.