It hardly matters if you have not qualified JEE Mains 2018. This is not the end to one's career in Computer Science. We have many private and government institutions still left which produce comparable results to IIT's and NIT's. 

If your son wants to study Bachelor's in Computer Science from Delhi, he can go for-

1. Amity University, Noida

2. Galgotias University, Noida

or apply for IPUCET or UPSEE exams if applications are open online till date.

There is nothing to worry about. 

Regards,

Keshav Sahani

hii

oh its not worry at all there are various colleges in delhi who takes in direct admission go with them while CSE is a pretty good branch as well

colleges are 

jaypee institute of technology

delhi technology university

amity university

many more above colleges are top one

all best