Botany

You need to discontinue the course and then take transfer certificate if you are studying in any other college under the same university. If you are changing university, you need to get a migration certificate from the university. Go through this process after the admission is confirmed.

I am also a class 12th student seeking for admission and I also got 81%. I think our destination is same.
I think we should wait for the DU cut-off, maybe in some courses like life sciences, we will get admission. Otherwise, we can find out some good private universities.

M.Sc botany, M.Sc in plants and biotechnology, etc.

Yes, bit a better advisable solution is to drop B.Sc and do Bachelor of designing either from NIFT or NID and if that is not possible for you, do a part time evening diploma from a good institute for example Mumbai University Garware institute offer such courses.