In Bengaluru there are only 2 Diploma in ME colleges which are Government colleges. The name of this colleges are provided below:

SJ Government Polytechnic, Bangalore

Government Polytechnic College, Immadihalli

Now there are numerous private colleges. To know about the private colleges you may visit the link below:

https://engineering.careers360.com/colleges/list-of-engineering-colleges-in-india?city=Bengaluru&ownership=Private&degree=Diploma&branch=Mechanical%20Engineering

To know more about the career in Mechanical Engineering visit the link below:

https://www.careers360.com/courses/mechanical-engineering-course

I hope this answer helps. All the very best for your future endeavors!