Most flywheels come off with a puller that threads onto the flywheel and then a threaded rod pushes on the end of the crankshaft until it pops off of its press fit. Be careful not to lose the key of the keyway that will be on the crankshaft in a groove. this keeps the flywheel from spinning on the crankshaft.
Most motorcycle flywheels need to have the center nut removed. You will need a flywheel holder to do this. Then you will need a puller to remove the flywheel itself.