How do i make him pay his debts to me?

I am 14 and this guy is 16. We were pretty good friends, me and my bestfriend (a girl) met him online and we came to meet him in a skatepark. we really liked it and decided to get some skateboards. he said he liked her and they kissed sometimes and he was so nice to everyone so i tought he was trustable. we went to the skateshop and got us 3 skateboards . She paid hers and i paid mine and his. He said he'll give me money in June but it's almost over and he hasnt given it to me yet. i kept telling him but he said he hasnt got it and he will pay me in June. He is leaving to another city in august so i need a way to make him gimme the money by the end of June.. What can i do? should i get some guys to take his skateboard away if he doesnt pay? or can i call the police? I have witnesses that i payed his skate. My friend, the skateshop owner and the workers there. what can i do?