Diploma

In order to apply for the lateral entry scheme, you must have completed Diploma in Engineering. The Diploma course is taken after completing 10th standard and once you have completed it the best option is to apply for Bachelor of Technology course.
The admission for Diploma student in Bachelor of Technology is given under the lateral entry scheme. By taking benefit of the scheme, the Diploma holders are eligible to take admission in the second year of B.Tech course.
There will be no need to pursue the first year of engineering, just take admission in the second year. By this way, the engineering course would be 3 years long for you instead of 4 years duration in normal circumstances.
Now, since you are taking admission through lateral entry, the following exams are useless for you.
IIT-JEE
ISEET
UPSEE
BITSAT
These exams are not conducted for the lateral entry students and therefore there is no point taking up these courses. At this moment I would also like to point out that there is no provision in Indian Institute of Technology and National Institute of Technology to take admission under lateral entry scheme. Therefore, you won't be able to take admission in these universities.
You will have to appear for the entrance exam called Lateral Entry Engineering Test. As the name suggests, LEET is conducted for the lateral entry admission. You should have 60 percent marks in Diploma to apply for this exam.
It should also be noted that there are various colleges that offer direct admission to Diploma holders. You can also apply in these colleges.