how to quit this?

[Bryce]

Well, you have a couple of options in my opinion. Firstly you could slowly stop watching them by instead of watching it every 1-2 days, you could watch it every 3-4 days, just make sure that you set an achievable goal. My second suggestion is that instead of watching pornography, you could just look at pictures/GIF's. I hope I have helped.

EDIT: As suggested by 'Sadsongs' you should replace the activity with something productive/constructive. In my case I started doing Air Force Cadets to keep my mind occupied.