As someone who has been lucky enough to have had great success overcoming Paruresis, I wanted to share my secret. This can't fail to work with everyone, because it is personal to everyone!
I started with a CBT book, the initial understanding that this is a phobia, linking the avoidance behaviors and increasing exposure was a real head start! Taking the role of an explorer, adventuring through my own body and mind, kind of conducting experiments to get to know, well to get to know myself and my body, was exactly what I needed!
Then there was the new fear, the fear of relapse, all stemming from a fear of not being in control (as I was later to discover).
To cut a long story short, my key to the almost complete dismantling of the framework of Paruresis in my mind, was / is meditation, more specifically vipassana meditation. Watching and learning both ones own body and mind, as well as the present moment (or reality) has resulted in an almost complete absence of the fear now. I take it one step at a time, I pushed it to a place where I was comfortable, then I stuck to that for years so that my brain didn't use the old framework. Occasionally I would push it and find new levels of comfort. I havent had the panic reaction in years, even though my life has had major ups and downs with times of anxiety, the Paruresis has remained dormant