Yowza, I've never seen that many! Seems like every year a few of my retained heifers get them and they eventually just go away, doesn't leave a noticeable scar. There are products like "warts off" and wart vaccines but I don't know how effective they are; some people rip 'em off with pliers.
We used a wart vaccine on some bought calves and they seemed to shrivel up and fall off but don't know for sure if it was the vaccine or time. They did seem to not try to "itch" them off as much. We will get a few on a calf or two a year and don't regularly vaccinate for it. Have a neighbor who religiously uses the vaccine and seldom see any on his. Don't think the vaccine will hurt so I would try it on him since he looks like they might be bothering him.