Can my boss do this?

I work in fruit and veg at a grocery store and have a tiny nose stud that I have agreed the entire time I have had it to wear a bandaid over it. One of my bosses decided today to make me wear a blue bandaid, which again no problem. But once my other boss seen it he said it looks stupid and that he doesn’t want me wearing my piercing at all. Can he do this? I have always complied and never had issues but I canttake it out for hours everytime at work as it closes up very quickly and it causes trauma to my nose. Any advice and is the boss allowed to suddenly make this demand?