I did my graduation in Electronics and I don't have the slightest idea WHY. And even after realising that it wasn't quite my thing, I continued. I shouldn't have.

However, there have been occasions when my hunch hasn't been right. After my graduation, I cracked the entrance of IIMC and DU LLB, I opted for Journalism at IIMC but after working for 3-4 years, I returend to pursue LLB because the subject of law.

so try to be as sure as you possibly can before giving up Engineering and opting law. Be Sure that you don't want to pursue Engg and be even more sure that you want to pursue Law.

Having philosophised a lot, and coming to your question, YES you can quit engineering and take CLAT or MHCET or any other entrance exam of any other university/institute offerinng 5 year integrated law program.

Now, 'top law colleges' is a very subjective term and since not all 'top law colleges' accept the same score, a good score for one college may not even be considered by the other college. Please check out this link - https://law.careers360.com/colleges/ranking to get a picture of what I am talking about. See what colleges interests you and which entrance exam score do they consider. Once you have figured out that, feel free to come back and ask more. 

However, to give you a very broad idea, the predictions for this year to get into top NLUs are - a score of anywhere between 125 - 148 out of 200 marks in CLAT.

all the best