how can I change the value on the waitforseconds in the inspector?

void OnTriggerEnter(Collider other)
{
this.gameObject.GetComponent().enabled = false;
StartCoroutine(FinishCut());
}

IEnumerator FinishCut()
{
    yield return new WaitForSeconds(4);
}

}

You can add a variable in your script and use that as argument:

   public float waitTime = 4.0f;

and change your code:

 IEnumerator FinishCut()
 {
      yield return new WaitForSeconds(waitTime);
 }