Collision2D.collider

Description

The incoming Collider2D involved in the collision with the otherCollider.

This collider is attached to the Collision2D.rigidbody.

Additional resources: Collider2D and Rigidbody2D.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    void OnCollisionEnter2D(Collision2D coll)
    {
        // If the Collider2D component is enabled on the collided object
        if (coll.collider == true)
        {
            // Disables the Collider2D component
            coll.collider.enabled = false;
        }
    }
}