Why when using Mathf Lerp the speed is not changing according to Time.deltatime? [duplicate]

Question

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class DetectCollision : MonoBehaviour
{
    public Transform player;
    public Transform target;
    public bool turnOnOffPlayerAnimator = false;

    float timeElapsed = 0;
    float lerpDuration = 3;
    float startValue = 1;
    float endValue = 0;
    float valueToLerp = 0;

    private Animator playerAnimator;
    private bool entered = false;
    private bool prevFacing = false;
    private Rigidbody rigidbody;
    private bool stopped = false;

    // Start is called before the first frame update
    void Start()
    {
        rigidbody = player.GetComponent<Rigidbody>();

        playerAnimator = player.GetComponent<Animator>();

        if (turnOnOffPlayerAnimator)
            playerAnimator.enabled = false;
    }

    // Update is called once per frame
    void Update()
    {
        var currFacing = IsFacing(target);
        if (currFacing != prevFacing)
        {
            // here you switched from facing to not facing or vise verca.
            timeElapsed = 0;
        }
        prevFacing = currFacing;

        var distance = Vector3.Distance(player.position, target.position);

        if (IsFacing(target))
        {
            if (entered && distance > 30)
            {
                if (timeElapsed < lerpDuration)
                {
                    valueToLerp = Mathf.Lerp(startValue, endValue, timeElapsed / lerpDuration);
                    playerAnimator.SetFloat("Forward", valueToLerp);
                    timeElapsed += Time.deltaTime;
                }
                playerAnimator.SetFloat("Forward", valueToLerp);

                valueToLerp = 0;
            }
        }
        else
        {
            if (valueToLerp < 0.9f)
            { 
                if (timeElapsed < lerpDuration)
                {
                    valueToLerp = Mathf.Lerp(endValue, startValue, timeElapsed / lerpDuration);
                    playerAnimator.SetFloat("Forward", valueToLerp);
                    timeElapsed += Time.deltaTime;
                }
                playerAnimator.SetFloat("Forward", valueToLerp);
            }

            Mathf.Lerp(valueToLerp, 0, Time.deltaTime * 0.0001f);
        }

        if(turnOnOffPlayerAnimator)
        {
            playerAnimator.enabled = false;
        }
        else
        {
            playerAnimator.enabled = true;
        }
    }

    private void OnTriggerEnter(Collider other)
    {
        entered = true;

        Debug.Log("Entered !");
    }

    private void OnTriggerExit(Collider other)
    {
        entered = false;

        Debug.Log("Exited !");
    }

    private bool IsFacing(Transform target)
    {
        Vector3 forward = player.TransformDirection(Vector3.forward);
        Vector3 toTarget = target.position - player.position;
        return Vector3.Dot(forward, toTarget) > 0;
    }
}

I tried first 0.1f but it didn't change the lerp speed.

I want that if the player is pressing the W key and moving the player forward and then stop pressing the key W it will smooth slow will lerp to 0. and it does but I also wanted to control the lerp speed.

I want that when the player is starting moving backward direction if the player leave the W key the player should stop slowly to 0. This should be the line :

Mathf.Lerp(valueToLerp, 0, Time.deltaTime * 0.0001f);

but the Time.deltaTime does not seems to affect the lerp at all. the lerp is working fine I just wanted to control the lerping speed too.