One best solution is to cut the internet connection. Without online access, that obviously stops online gambling addiction.
Stopping a bad habit should take a gradual process, if it is muscled like you illustrated here, the possibility of that same person going back to it and becoming even worse than before is high. Addiction to gambling should be regulated progressively until it can come to a halt. The first step is to have a gambling budget and discipline yourself not to exceed that budget. Secondly, you'll should have a gambling time table and not indulge in it daily, have duration you are expected to gamble on the days it falls into the plan, so for example, if you were gambling for 10 hours a day, you can start by reducing the budget to 10% of your earnings and the time to 3 hours daily, you also need to find a new hobby to replace the gambling. This new good hobby will now be your new addiction instead of the gambling. It might be reading, learning a skill, a new career, new job e.t.c. After two weeks of keeping to that discipline strictly, you can further reduce the days to 5 days and week, then 4 days and gradually, you'll see that you only gamble once again week and if you can maintain 3hrs and day, once again week for three months, you'll see that the drive for gambling in yourself lifestyle must have seriously reduced, if not vanished and you would start living and new and better life. The new hobby you've trained yourself to get addicted to all these while will replace gambling for you and you're are advised to improve consistently on it, lest idle times can make your prone to going back to your rejected old life of gambling addiction.
So, in a nutshell, gambling addiction can best be stopped by introducing a new, good addiction to substitute the gambling addiction. the progressive transition process will gently direct your mind to focus more on the new habit and devout the same energy which you formerly deposited into gambling to the new found addiction. This new hobby will in turn straighten your life and free you from the uselessness of gambling addiction. You don't just take something away, you replace it with something better.