I was a total sugar addict, a big biscuit and chocolate eater. I've been doing the no sugar/crap/processed food thing for ten weeks now. I love it. I've lost 16lbs so far. I've found it easy, still been out for lots of meals, drinks, had the odd treat/dessert when out.
Have a look at the Giving up sugar for January thread, it helped me. It's still going, although a bit quiet nowadays. The I Quit Sugar page on Facebook is good for ideas. The hypnotherapy book for sugar by Paul Macenna is good too, although I just used it for facts rather than all the hypno techniques.
You can do it! I went vegan and no sugar once and the first week SUCKED. Bad mood, headaches, it was horrible. Once I pushed past it I felt amazing and lost two stone in two months. That was a few years ago now and I'm still pissed off at myself for falling off track. I don't know of any apps but I just made everything my self as much as I possibly could.