How do you nicely tell somebody your not into them?

So there is this kid who I used to be friends with but now he won't stop texting me. Now he has asked me to go golfing with him and I do not want to go at all. One I would be terrible at golfing and I DO NOT want to spend hours with him just the two of us. I want him to stop texting me so when h does I ignore them but he doesn't seem to get the message, what do I do?