How to hide body from an http post ( where it contains the password ) of people who are analyzing network traffic?

Question

Good morning beast... I have a windows application accessing a web api in the cloud and picking up some security data from my system... this api is for exchanging information only with my windows application, so I protected it with Oauth ( bearer ) and I only required accepting https connections.

I have other computers in my workplace with this windows application installed, I will in any of them and install a network traffic monitoring program ( Fiddler ) and quickly can see the post body ( containing my password ).

How to prevent other people with access to these computers from doing the same and discovering my api password???

Somebody please help me, I’m already crazy with this thinking there’s no way!

I access the api with the code below:

HttpClient clienteHttp = new HttpClient();
System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls;
clienteHttp.BaseAddress = new Uri("https://meuUri.com/");

   Dictionary<string, string> tokenDetails = null;
   var login = new Dictionary<string, string>
   {
      {"grant_type", "password"},
      {"username", "meuUserName"},
      {"password", "meuPassWord"},
    };

    string result = "";

    var response = clienteHttp.PostAsync("Token", new FormUrlEncodedContent(login)).Result;
    if (response.IsSuccessStatusCode)
    {
       tokenDetails = JsonConvert.DeserializeObject<Dictionary<string, string>> 
          (response.Content.ReadAsStringAsync().Result);
       if (tokenDetails != null && tokenDetails.Any())
       {
          var tokenNo = tokenDetails.FirstOrDefault().Value;
          clienteHttp.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", 
          tokenNo);
          HttpResponseMessage resp = clienteHttp.GetAsync("api/clientes/"+idCliente).Result;
          resp.EnsureSuccessStatusCode();
          result = resp.Content.ReadAsStringAsync().Result;
        }
    }
   MessageBox.Show(respostaApi, "xMarket", MessageBoxButtons.OK, MessageBoxIcon.Information);