the 3/8" reverse threaded nut on the right hand side of the engine is correctly removed with a breaker bar or a impact driver.
However, this will reveal your magneto, not the clutch. The clutch controls your drive pulley and variator, and therefore is located in the vicinity of the belt, on the opposite or left hand side of the engine. You will need the proper puller tool to remove the clutch drum. Be also wary that you don't smach the grease fitting in the end of the crankshaft.