Hello Saunak,
Please remember if you have pursued diploma after class 12th then you may pursue BBA, however if you have pursued diploma after class 10th then you are not eligible for admission in BBA program.
Please remember in order to pursue BBA you need to be 12th pass from any stream with good academic record preferably 45%-50% in 12th, plus you need to take entrance test conducted by various institutes.
Hope this information is helpul!!