From Halopedia, the Halo wiki

Vandalized is an achievement in Halo: The Master Chief Collection. This achievement is obtained by finding the graffiti on the level NMPD HQ.

The graffiti can be found in the second area, where Buck says, “Jackals with Carbines up top. Watch yourself!” Since the achievement cannot be done in Theater mode, players need to jump off the wall opposite of the door leading into the area. The graffiti is facing away from the building and needs to be within the view of the player’s HUD when falling off the roof.