It would be even better if You have asked the question with Mentioning the reason. If there is Not any solid reason for leaving 12th class then I would say please don't leave this opportunity. Now you don't want to study but at later times you may get interested. If you don't want to study any more than Just complete 12th class It will help you in Future to get good Jobs and even You can also complete your graduation with distant learning.

Anyways if You have decided to quit 12th, You have a lot of Job opportunities Both in Govt as well as Private sector. In the govt sector, You can apply for Indian Railways, Police, Indian Army Navy air force. Many Private companies will give you jobs based on your skills.  Or else You can work on your skills by taking courses on ITI.