I want to break connections with an autistic friend.
Just because they are autistic?
No. It's because I can't stand his failures anymore and I'm tired of hearing about them.
You are under no obligation to remain friends with someone forever. However, if they are your friend, you must have cared about them at some point. Perhaps try talking to them about how much they talk about their failures.
I don't know if I care enough to be bothered to do that.
If you're that unhappy with the friendship that you don't even want to talk to them, then maybe it's best just to end it. You don't need to feel obligated to stay friends with someone if you are no longer satisfied with the friendship. Just be nice about how you end it so you don't upset them.