I have a gameobject with a box collider using c# how do i destroy it when the player touches it?

the example there is almost exactly what you want.

just need to change it to:

public class ExampleClass : MonoBehaviour {
    void OnTriggerEnter(Collider other) {
            if (other.gameObject.tag == "Player"){
                Destroy(gameObject);
            }
    }
}