Can I pursue M.Sc maths from T.R. College of Education after B.Tech?

Yes, you are eligible to apply for M.Sc (Mathematics) after completion of your B. Tech (Mechanical). After completing M.Sc (Mathematics), you will have great scope of career opportunities. MSc in Mathematics: Eligibility Criteria Passed BSc (Mathematics) or BSc (Mathematics with Computer Science Ap

The eligibility criteria says that a candidate should have bachelor degree with the mathematics subject atleast for two years. And you are not a mathematics student so you would not be able to do MSc in maths.