I got 80percent in JEE and 12600rank in SC category is it necessary to write mhcet

Hello Shivateja!

Giving another entrance exam won't  waste anything.
It will only bring benefits.
It will increase your probability of getting more and more colleges.
It will also give you another chance to perform better than before.
Below given is a link of college predictor that can help you get an idea of your chances to get colleges based on your JEE Main marks:-
https://engineering.careers360.com/jee-main-college-predictor?utm_source=google-search&utm_medium=paid&utm_campaign=jeemain-clgpd

Hope this helps :)
Best of luck!