Hello Gitanshi, 

There are numerous lines you can take if you decide to quit marine engineering. 

1. You can sit for the civil service exams and pursue high ranking government jobs. 

2. You can do MBA. 

3. If you have a class 1 or chief Engineer's certificate of competency then you can work as a surveyor for classification societies. 

4. You can teach at the Maritime Institute

5. You can be a part of the MMD surveyors

6. You can be fleet superintendent after being chief Engineer

7. You can work in shipyards

8. You can work in ship broking and chartering

9. Last but not the least, you can try out entrepreneurship ventures or try to indulge in business. 

Hope this helps  :)