Which exam should I take in order to pursue MBA or M.Tech abroad?

For MBA, you should take GMAT and for B.Tech, you should take GRE. But some universities offer admission on the basis of IELTS.

For MBA, you need to be a graduate. You can first pursue B.Tech from some college, then you could do your MBA from the college you wish to. M.Tech can also be done after B.Tech