I think now that someone has confessed to you, if you particularly like him, you can reply that we can talk. If you don't like it, you can also tell others clearly that it is not suitable to reject him directly.
For example, I have a neighbor whose family is a boy. When it was time to go to school, a girl confessed to him, but he didn't want to, and he didn't like that girl. Later, he refused directly, saying that I don't like you. I think this will do. If it is delayed, it is also possible.
For example, if I don't want to fall in love at school, it's ok. I think this method is still good.
But you can also say that although we said we couldn't fall in love, we said we could go out as friends, which is ok.