How to connect onCollisionEnter with another rigidbody via tag,Problem with collision touching a rigidbody

I have been trying to work on my collision for the object in my game so where it touches a surface (in this case a tilemap surface) it will destroy the bullet, but I am confused on how to set the rigidbody that it needs to destroy to the surface does anyone know how to properly use Collisions2D.gameObject.tag?

 void onCollisionEnter( Collision2D Other )
 {
     if( Other.gameObject.tag == "Tilemap" )
     {
         Destroy(this.bullet);
     }
 }