Very much like toenails, Laura. Best way to trim them is with a Dremmel power tool and a cutoff wheel. The spur should be cut about 3/8" from the leg. The action of the wheel will cauterize the cut and very little, if any, blood will leak. If you have bleeding, a little pressure will stop it in a few minutes. Get someone to hold the rooster as the vibration will make him struggle a little. They don`t feel pain the same way we do, so you aren`t hurting him and when you put him down afterward, he will act as if nothing happened. This is don` all the time and isn`t something to shy away from..........Pop
Spur trimming can get emotional on here as you might imagine. In my opinion, it is a tool that can be used if necessary. It is not something I would automatically do but would not hesitate if it was needed. Personal choice.
This link has some videos and discussion on the topic.