There's a never ending supply of douchebags in this world. Such a shame.
Or if I were unhappy, I would talk to the artist and/or the mural organization about it, ideally before they had put too much time into the project.
I certainly wouldn't wait more than a decade after the murals were finished and then on a whim decide to paint over them, erasing months (?) of artists' efforts in an afternoon.
I don't know why you are putting "mural" in scare quotes. The works in question are clearly murals, not just graffiti tags or something.
We must organize a special police unit to sweep the streets guns akimbo and end this public nightmare once and for all!