Prospects of getting the pulley off by destroying it without damaging the output shaft are not good. What I suggest you do, is soak the junction between the pulley and the output shaft in penetrating liquid (such as Penetrene or similar specialised penetrant, but not WD40 or similar, which does a poor job as a penetrant) for a day or so, then be sure you've removed the grubscrew, and use a correctly-sized gear puller to pull the pulley off. Correctly done, this will not damage anything and except for waiting for the penetrant to take effect, requires very little time or effort. If it turns out your shaft is particularly rusty and particularly tight, you may end up having to heat the pulley, but this is semi-desperate stuff, since it will destroy the output shaft's oil seal.
