The only method that actually works is Go Cold Turkey. This phrase is frequently used in stopping addiction. It means that you should stop abruptly and never go back no matter your intensity to use it again. You will have to drive your attention on somethign else to stop addiction.
The only way you can be able to do this kind of a thing is to eliminate all that is going to bring you close to how you used to gamble because once that temptation is always in your face, you will find it very difficult to resist going back to it, but if you are able to cut everything out, you will stand a chance of stopping it.