There are lots of proposals. Recently, he retweeted a pundit who said that murderers should be hanged and that Europe achieved its level of civilization by executing 1-2% of its population for eugenic purposes:

https://xcancel.com/elonmusk/status/1992599328897294496#m

You know the world is heading in a good direction when the world's richest man with nearly half a trillion dollars is starting to muse about whom he wants to start killing off. You know, for the "common good".