How can I create a toggle between an Unlocked and Locked camera?

I'm trying to create a MOBA or RTS style camera system and want to be able to switch between a camera that follows my character with its movement, and one that is "unlocked" from the player so it stops following it and I can bring my mouse to the edges of the screen to move the camera.

I have the code for each one, but can't figure out a way to do something along the lines of: Press Y to lock on to the character and U to unlock for example. Or press the same button twice to toggle.

Here is my Locked code:

 public GameObject player;
 private Vector3 offset;
 // Use this for initialization
 void Start () {
     offset = transform.position - player.transform.position;
 }
 
 // Update is called once per frame
 void Update () {
     transform.position = player.transform.position + offset;
 }

And here is my Unlocked code:

 private Vector3 desiredPosition;
 public float scrollZone = 5;
 public float scrollSpeed = 20;

 public float xMax = 18;
 public float xMin = 0;
 public float zMax = 8;
 public float zMin = -8;
 // Use this for initialization
 void Start () {
     desiredPosition = transform.position;
 }
 
 // Update is called once per frame
 void Update () {
     float x = 0;
     float y = 0;
     float z = 0;

     float speed = scrollSpeed * Time.deltaTime;

     if (Input.mousePosition.x < scrollZone)
         x -= speed;
     else if (Input.mousePosition.x > Screen.width - scrollZone)
         x += speed;

     if (Input.mousePosition.y < scrollZone)
         z -= speed;
     else if (Input.mousePosition.y > Screen.height - scrollZone)
         z += speed;

     Vector3 move = new Vector3 (x, y, z) + desiredPosition;
     move.x = Mathf.Clamp (move.x, xMin, xMax);
     move.z = Mathf.Clamp (move.z, zMin, zMax);
     desiredPosition = move;
     transform.position = Vector3.Lerp (transform.position, desiredPosition, 0.2f);
 }

Currently I am using them together by starting the game unlocked and holding the space bar to enable the lock. Like this:

 public GameObject player;
 private Vector3 offset;

 private Vector3 desiredPosition;
 public float scrollZone = 5;
 public float scrollSpeed = 20;

 public float xMax = 18;
 public float xMin = 0;
 public float zMax = 8;
 public float zMin = -8;

 // Use this for initialization
 void Start () {
     offset = transform.position - player.transform.position;
     desiredPosition = transform.position;
 }
 
 // Update is called once per frame
 void Update () {
     float x = 0;
     float y = 0;
     float z = 0;

     if (Input.GetKey (KeyCode.Space))
     {
         transform.position = player.transform.position + offset;
     } else if (Input.GetKeyUp (KeyCode.Space))
     {
         desiredPosition = player.transform.position + offset;
     }

     if (!Input.GetKey (KeyCode.Space))
     {
         float speed = scrollSpeed * Time.deltaTime;

         if (Input.mousePosition.x < scrollZone)
             x -= speed;
         else if (Input.mousePosition.x > Screen.width - scrollZone)
             x += speed;

         if (Input.mousePosition.y < scrollZone)
             z -= speed;
         else if (Input.mousePosition.y > Screen.height - scrollZone)
             z += speed;

         Vector3 move = new Vector3 (x, y, z) + desiredPosition;
         move.x = Mathf.Clamp (move.x, xMin, xMax);
         move.z = Mathf.Clamp (move.z, zMin, zMax);
         desiredPosition = move;
         transform.position = Vector3.Lerp (transform.position, desiredPosition, 0.2f);
     }
 }

Any help or suggestions are very appreciated(: