First You go get a Chastity cage that's 1/2 shorter then your dick is soft and start wearing it 24-7 only take it off to clean and shave.
Then start googling what herbs block Testosterone and what Herbs Have high contents of Estrogen and start a regiment.
I have went from almost 7 in hard 5 soft down to 1 in soft and 2.5 hard. I was recently castrated and I am still taking the estrogen herbs.
I also have a nice set of c cup moobs now.