RaycastHit.collider

Description

The Collider that was hit.

This property is null if the ray hit nothing and not-null if it hit a Collider.

using UnityEngine;

public class Example : MonoBehaviour
{
    void Update()
    {
        if (Input.GetMouseButtonDown(0))
        {
            RaycastHit hit;
            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);

            if (Physics.Raycast(ray, out hit))
            {
                if (hit.collider != null)
                {
                    hit.collider.enabled = false;
                }
            }
        }
    }
}

Additional resources: Physics.Raycast, Physics.Linecast, Physics.RaycastAll.