I am debating on whether to quit after 2 year? The motivation that I once had is no longer there. Lately, I lost interest in the PhD program/on the research 1) I am not learning new things and not showing progress 2) I didn’t like the name of the PhD, PhD in …. 3) Not sure what is available after PhD, 4) I don't want PhD degree, I just want to work in a private firm, if I have PhD I will be overqualified. I started looking for a job and recently I was offered one, I have accepted the offer. What should I say to my supervisor? This is too sudden and shocking to her? She is a very nice person to me and she trusts me a lot. I wasted her time and precious funds? I have already decided to quit, I know to walk away after two years is a shame, but I have no interest left. please give me some advice?

Just explain it to her and she'll understand as a PhD isn't for everyone and not very useful if you work for a private firm. You gave it a shot and it didn't work out - you could say your priorities have changed and you realise that this isn't for you and you want to refocus your efforts and thank her for time etc... You could turn your work so far into an MPhil and that way you still get something out of the last two years. Good luck.

Kuman - sounds as if you have made up your mind, so fair dues. From the forum, ya can see a lot of us still are all over the shop.
Congrats on the job offer and in fairness, if the interest is gone and you do know what you want, the decision is made up. Yeah, chances are is that the initial time you tell the supervisor is gonna be frosty, but she should recognise that there is no point carrying on. If ever there is a positive way to leaving the PhD early, this is it - you are not leaving in spite or due to differences of opinions. And besides, the only person that you are ultimately answerable is yourself.

Talk to your supervisor - is there a way to finish with a Masters, doing it part-time? In that way, it is not the worst case scenario for both of ye and you prob. have enough to form the basis of this. Just an idea.

Congrats and good luck dude