Dear Aspirant,

As per the official site IIIT Delhi don't have a lateral Entry in Btech Mechanical. Following are the courses they have:

BTech is offered in the following disciplines
Computer Science and Engineering (CSE), Computer Science and Applied Mathematics (CSAM), Computer Science and Design (CSD), Computer Science and Social Science (CSSS), Computer Science and Biosciences (CSB), Electronics and Communications Engineering (ECE), Computer Science and Artificial Intelligence(CSAI)

Hope this helps. Thank you.