I’ve been there. I know the struggle. This is my 3 step program.
1)Before you do anything ask Hashem for help. Sincerely daven EVERY morning (in whatever language you prefer), tell Him about this difficulty,and ask Him to help you stop.
2)Find a hobby. Do something that you love. Take a course, paint, knit, exercise, cook, eat, jog, start a blog, or something easy and light to unwind after a long day…be adventurous and try new stuff. You must keep yourself busy. Being bored will lead to trouble.
2)Toss it. Delete them from your computer, toss out the discs, install a filter to block you from those sites and don’t write down the password. Do what you have to to make sure you stay away from it.
The reason why I wrote find a hobby before tossing is that you need to have something to do instead of watching. You can’t just stop cold turkey and have nothing to do in it’s place.
It’s very difficult to do, but you’ll be a better person for it.
Much Hatzlachah.