if I go to coaching class for whole 1 year.is it possible to clear iit JEE main advance and main ??

Definitely, taking coaching is good option to prepare for JEE mains and advanced as it ensures thats students study regularly. However, noone assure the clearance of exam as it entirely depends upon how focused the preparation is going. Further, one can follow the below tips too:
Tips and Tricks
Candidates must attempt questions carefully.
Candidates must revise their school-based concepts.
Take online mock tests to know your strengths and weaknesses.
Candidates must practice placement papers and mock tests to prepare well.