You are now only 19 years old and you have already joined Central Government. My congratulations!
I know that you have been posted in Delhi or in any other bigger cities of India as you have qualified SSC CHSL. So, you must not resign. First, qualify your B.Sc. Examination from IGNOU. Use the Study Centre of your city. If your Study Centre is in a different city, you can register yourself in a Study Centre in the city where you are working.
After qualifying your B.Sc. Examination, lots of opportunity in Government sector will come to you. Not only Bank Probationary Officer (P.O.), you will also be eligible for applying for higher-level posts of SSC (SSC CGL), various posts under different Railway Recruitment Boards and also for Civil Services Examination
conducted by UPSC. You can also apply for the Public Service Commission posts in your own state.
As you are posted in a big city, you will get the coaching facility for various recruitment examinations in your city. As you are already working, you can finance the coaching fee. So, don't resign your present post. If necessary, you can take long leave (Leave Without Pay) for a maximum period of five years.
Last but not least, I must state that nowadays SSC CGL posts are considered more lucrative than Bank P.O posts. In my office itself, two Assistant Section Officers have joined in last three years resigning the position of P.O.