How do I tell him?

So beginning of September I started talking to this guy and we hit things off and we went on a couple of dates only kissed once. we have a lot in common, he's a very nice attractive smart guy. Then I met another guy a couple of weeks after and he's everything I've ever wanted in a guy and I really see myself with him in a relationship. We've also been on a couple of dates and we've made out many times. He has a ton of amazing qualities. And I just feel comfortable with him. I just don't know how to tell the first guy that I want to stop seeing him. I've stopped with the flirty texting and I haven't seen him in 2 weeks. And he keeps flirting and asking to hang out but I don't know what to say. I've never had to do this before and I don't know how to do it. In person? Over phone? He also gave me a stuffed animal do I give that back?? I really don't want to hurt him but I know that's going to happen. 😔