An object reference is required to access non-static member `UnityEngine.Component.transform'

I’m very confused as to why this won’t work, all I’m trying to do is make the box-collider drop down a little when my slide function is called, everything else is working fine but if anybody can explain to me why this doesn’t work it’d be highly appreciated.

using UnityEngine;
using System.Collections;

public class JumpScript : MonoBehaviour {

	Animator anim;
	public AudioClip JumpSound;
	public AudioClip SlidingSound;
	public float jumpSpeed = 1000f;
	float jumpRate = 1.0f;
	bool canJump = true;
	public float slideTime = 1.0f;
	public float timeHeld;

	void Start()

		this.GetComponent<AudioSource>().clip = JumpSound;
		anim = GetComponent<Animator>();

	void Update() 

		if (Input.GetKey(KeyCode.Space)) timeHeld += Time.deltaTime;
		if (Input.GetKeyUp(KeyCode.Space) && timeHeld <= slideTime) TryJump();
		if (Input.GetKey(KeyCode.Space) && timeHeld > slideTime) Slide();
			timeHeld = 0f;

	void TryJump() 
		if (!canJump) return;

	IEnumerator JumpCooldown() 
		canJump = false;
		yield return new WaitForSeconds(jumpRate);
		canJump = true;
		yield break;
	void Jump() 
		rigidbody2D.AddForce(new Vector2(0, jumpSpeed));


	void Slide() 
		BoxCollider2D.transform.Translate(new Vector2(0, -1));


Your problem is exactly what it says. In line 68 you have:

BoxCollider2D.transform.Translate(new Vector2(0, -1));

BoxCollider2D is a class, transform is an instance field not a static field. You can only access it on an instance of a class,
not the class itself.