It is entirely dependent on your job goals. Without assessing the benefits and drawbacks as well as your priorities, no decision may be wise or foolish.
Advantages of becoming an SBI PO:
Cons of working as an SBI PO:
Advantages of pursuing an MBA:
Cons of pursuing an MBA:
It is up to you to decide whether it is a sensible move to leave your SBI PO job for an MBA from SCMHRD based on your priorities. You might even try this career while continuing to prepare for a better college or a 1-year MBA school if you are eligible to reduce opportunity costs.