Hello Padmavati, 

To sit for KCET,  you need to qualify i.e pass in your 10+2 examinations and have at least 45% aggregate or 50% (for b.arch) . If you don't have the 10+2 qualifying certificate, I am afraid you cannot apply. You can learn more about KCET eligibility criteria here : https://www.google.com/amp/s/engineering.careers360.com/articles/kcet-eligibility-criteria/amp

Hope this helps.