hi,

see you need to directly contact with college authority for management quota admission, since it varies time to time, most of the government college takes admission based on entrance exam score and rank, but most of the  private colleges has management quota, I have given a link below where you may find different colleges of india for admission in diploma in civil engineering.

https://engineering.careers360.com/colleges/list-of-diploma-in-civil-engineering-colleges-in-india