You will need to use something you can open and get around it. A dog nail trimmer, hoof nipper, or even a good wire cutting pliers. Cut about in the middle, have either a kwik stop type product on hand for bleeding, or something like flour or corn starch. Try to avoid cutting the quick but be prepared for it. Just press that stuff onto the bleeding stub. You will have to see how damaged the leg is, but it should heal up without any intervention. Spurs should be checked and trimmed about twice a year to avoid it happening again.