College Admission problem

Im a Class 12 student currently studying from a private school cbse from Delhi ... I have a SC Certificate issued by Govt. Himachal..im bonafide Himachali...For admission at DTU, Delhi... It is required that Sc/St/ObC certificate must be issued by Govt of NCT of Delhi only... Nw hw do i get these Certificate...my cast comes under SC in Himachal, SC in central list and OBC in delhi... ?? hw cn i get obc certificated from delhi......?