It's ok to cut people out of your life, should you choose.

When he's not using his computer use his account to watch some more wholesome videos like wood working, gardening or car modification, and delete as much of the nonsense from his history as you can, the algorithm will then sort him out

I have really bad depression, but I still don't think I hate myself enough to spend my free time watching brainwash content to try to convince myself I'm better than Mexicans. Your dad needs to get a hobby and have an identity beyond "republican".

He's an addict. He gets little hits of oxytocin, dopamine, and endorphins from watching videos that confirm his view of the world and his place in it. I'm not sure what advice to give you. Yo might try looking up de-radicalization groups, or someplace like Life After Have or Parents for Peace.

I've got some friends who also became Zionists following that same pipeline. A few formerly friends of mine think that Zohran Mamdani wants to completely extinguish and eradicate all whites in New York and that the elections have been frauded because he thinks that even illegal immimgrants voted with the only purpose of exterminating all whites in a genocide aimed at creating an Islamic state and then invade america to remove it from history. Crazy shit

You should help your dad before he does something really really dumb