Question

what can we do if some people write their names or massages on the walls of monuments

Answer 1

we should advise them not do such type of things and tell them that we making monuments sad by scribbling in the walls.

Answer 2

we should tell them we should not scribble on monuments
we should explain them the importance of monuments
we should tell them that we should make our country a tourist spot
we can tell the consequences of scribbling on monuments