Here is how I clean turkey spurs.
Using a sharp hack saw I cut the legs on either side of the spurs.
Next I use a razor blade to remove the skin and tendons. I also take a nail or pipe cleaner to push the marrow out of the leg bones.
I then wash the spurs with soap and water and set them aside to dry overnight.
After drying overnight, I used the hack saw again to trim the sides down a bit so the bone was only as wide as the spur. This is just my personal preference. You could leave more bone on if you wanted. Then I use a Dremel to grind off any dried cartilage or other bird material and also to smooth out any hack saw cut marks on the ends of the bone.
The final step is optional but I like to whiten the bone a little. I wrap each spur in a thin strip of paper towel and then put masking tape over the paper towel. I fill a small cup with hydrogen peroxide and set the spurs in the cup. The paper towel acts as a wick to draw the peroxide up and the tape helps keep the spurs from tipping over in the cup. I have found that some bones whiten better than others with this method. One thing to watch out for is that sometimes the peroxide can get wicked up under the spur and will start to lighten the base of the spurs. If you see that I would take the paper towel off and call it good unless you want semi-bleached spurs.