Can I apply for an HR post after B.Tech?

You can apply for HR post but generally companies prefer MBA HR specialization. So, you should have valid reason why you have not chosen MBA instead of B.Tech and you should be convincing at the time of interview.

Dear Yash, Yes, you can but you should go for MBA programme as HR specialisation. Then, you would get good companies as campus placement for HR profile. Plan for top institutions for your further education for better placement and knowledge too. All the best.