I am an IIT aspirant for which I m preparing at a local coaching.I am presently studying in Kendriya Vidyalaya which is very strict for attendance and is not flexible at all when it comes to assignments. It is creating problems in my preparation. I am not at all interested in taking drop. Teachers also treat me different as I have joined IIT coaching. I m thinking to leave the school and opt for some dummy school before CBSE registration commences. Is it a good decision?

@ arapan 
NO , kindly dnt opt for dummy school . 
whereever u are now , that are excellent , what i can say about iit preparation is that as u are a cbse student , then , in school u can complete 40 percent of the jee prep . 
just focus what they are teaching in class from ncert and try to cover ncert in school only , and in jee mains 50 -60 percent ques are from ncert only . 
so, after coming from school , u can do self study with the local coaching notes , or even u can opt for askiitian package also for prep . 
and 1 more thing – DNT GO WITH DUMMY SCHOOL , if u will join then , your concentration will not be full by studying in home , i have seen many student thinks that joining  the dummy school and will prepare at home , but they are less sucessfull . 
so, FOCUS ON YOUR CURRENT STRATEGY . 
AFTER SCHOOL JUST DO 4-5 HOURS OF SELF STUDY OF JEE LEVEL , THATS ENOUGH 
ALL THE BEST ..