Hello,
No you can't do that. You have to appear entrance for lateral entry as you have studied diploma. You will get an admission one 2nd year in any college you go. You can't leave any degree or course and join another. This is not like a playground. Anything realed to studies or career it has a path to be followed. You can leave anything anywhere you feel like.
So just complete your diploma and go for engineering or any other course you want to.
Neither you can change your branch now not your degree.
Hope it helps