I guess it all depends on the kind of Drug you would like to quit and your personal situation. Hard Drugs are way more difficult to overcome and most people take them because they have serious personal problems. In that case Rehab might be the only chance and even then it is not easy.
I was addicted to cannabis for almost 10 years and quitting was pretty easy because I had an awesome situation with travelling around the world a having a really nice girlfriend (Still have). So quitting kind of happened because my life was awesome enough and I did not need it anymore. Now Cannabis is not a problem for me anymore, some how never was... At the moment I just prefer staying sober but would not mind a smoke with friends once in a while.
Alcohol on the other hand is something more dangerous. Especially because it is legal many people underestimate the addiction. You must be aware that alcohol kills people every year. My father was an alcoholic and it killed him too. One of my best friends died because he was drunk driving. SO for me alcohol is the worst drug of them all and quitting is really difficult because everybody around you drinks regularly but after you were addicted you cannot go back to normal.
And concerning the question: There is no easy or quick way to quit a Drug. It is always difficult and never quick.