My purpose in supporting him would be indeed to kill the republican party...at a minimum to kill it as it currently exists.
Trump bids fair to upset a lot of traditional GOP applecarts.
So you understand how ridiculous it would be for any Trump supporter to argue that anyone should support Trump to prevent Hillary from being elected - since Trump supporters quite regularly proclaim that if Trump is not the nominee, not only will they not vote for the GOP nominee for president, but many will vote for Dems at all levels. It seems that Trump supporters are fine with Hillary winning and having a Dem Congress if Trump is not the nominee, but become scandalized that others would be fine with Hillary winning and having a GOP congress if Trump does get the nomination.