I'm going to make my friend receive a 0 on an assignment
Why would you want to make your friend get a 0?
Because I'm a very evil person and I want to ruin his life.
You don't have to help your friend but you shouldn't make things more difficult for him and make him get a 0. It will ruin his life and you will feel bad about it.
Why should I care? I don't really like him that much.
If you don't like him then you should leave him alone, not make cause him to get a bad grade. Doing so just makes you seem mean. I think it would be better if you didn't interfere with his grades at all.