Web API 404 error Delete request

I have a Web API that worked perfectly on development with all kind of HTTP requests (on the same controller), once I moved it to production (shared server, I don't even have access to it) the DELETE requests stopped working (the others are working fine), I get a 404 error:

Requested URL https://www.example.com:443/Rejected-By-UrlScan~/API/Users/DeleteUser/1

Physical Path d:\xx\yy\example.com\Rejected-By-UrlScan

Logon Method Anonymous

Logon User Anonymous

This is (a part of) the web.config:

 <system.web>
    <customErrors mode="Off"/>
    <authentication mode="None" />
    <compilation debug="true" targetFramework="4.5" />
    <httpRuntime targetFramework="4.5" />
  </system.web>
  <system.webServer>
    <modules runAllManagedModulesForAllRequests="true">
      <remove name="WebDAVModule" />
    </modules>
    <handlers>
      <remove name="WebDAV" />
      <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
      <remove name="OPTIONSVerbHandler" />
      <remove name="TRACEVerbHandler" />
      <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
    </handlers>
  </system.webServer>

The Delete Action:

[Authorize]
[RoutePrefix("Users")]
public class UsersController : ApiController
    {
    [HttpDelete]
    [Route("DeleteUser/{id:int}")]
    public void Delete(int id)
    {
        _UsersRepository.Delete(id);
    }

And the AJAX call:

deleteUser = function (id, callback) {
    $.ajax({
        url: "../API/Users/DeleteUser/" + id,
        type: "DELETE",
        success: function () {
            callback;
        }
    });
}

WebApiConfig.cs:

    public static void Register(HttpConfiguration config)
    {
        // Web API configuration and services
        // Configure Web API to use only bearer token authentication.
        config.SuppressDefaultHostAuthentication();
        config.Filters.Add(new HostAuthenticationFilter(OAuthDefaults.AuthenticationType));

        // Web API routes
        config.MapHttpAttributeRoutes();


        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );

        //create json formatter and remove all others
        var jsonFormatter = config.Formatters.OfType<JsonMediaTypeFormatter>().First();
        jsonFormatter.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();
        jsonFormatter.SerializerSettings.Formatting = Newtonsoft.Json.Formatting.Indented;
        config.Formatters.Remove(config.Formatters.FormUrlEncodedFormatter);
        config.Formatters.Remove(config.Formatters.XmlFormatter);
    }

An example of a working call on the same Controller:

getUsers = function (callback) {
    $.get("../API/Users/GetUsers/", callback);
}

And the Action:

[Route("GetUsers")]
public IEnumerable<User> GetUsers()
{
    return _UsersRepository.GetUsers();
}