It depends. If they are long and mature, they can be cut at about .25 inch from the shank and usually there is blood and needs to be cauterized.
Some folks twist them off with a vice grip or similar tool. I generally cut them with a small carborundum tool, then cauterize. In time, they will grow back. A valuable bird can be maintained early and often, covering the 'burned' spur stub with a medicated ointment like Kendall Udder Cream, made by Ken Ag. Top quality product!!!
I agree the Udder Cream like many products is good stuff.
So if there's bleeding removing the spur either by cutting or twisting off then there must be nerves too - causes some pain to the roo I imagine?