Gift him submarine tickets.

Stop giving him your money for starters.

1. Stop giving him money. Get off twitter completely. Never buy a Tesla.
2. Get other people to stop giving him money. Call your government representatives, your local media, the national news services, etc., and make it clear that being on Twitter is linking them directly to antisemitism, white supremacists, and Nazis.
3. Get him fired. Buy stock in Tesla (Twitter and SpaceX are both private) and vote against him being on the board or executive. Show up to shareholder meetings. Raise a stink. You won't be able to buy enough to sway the board, but if 5000 people with tiny holdings show up in person to an AGM and stand against him (and if every one demands the mic), the board can't help but take notice - and the negative media coverage would be great.
4. Get the governments to stop giving him money. Lobby your representative (if you're in the USA). Make it clear that funding Musk, funding Tesla, funding SpaceX, all mean directly supporting antisemitism.
5. Call your representative (yes, again! Make Musk their personal nightmare!) and demand that he be charged with hate crimes.

In other words, stop giving him money. Take away his authority and power. Isolate him from the things that are feeding his bank account and influence. Leave him hanging in the breeze.