Here a solution which uses the window handle and an imported SetWindowPos() native function to achieve what you are looking for:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleWindowPos
{
    static class Imports
    {
        public static IntPtr HWND_BOTTOM = (IntPtr)1;
       // public static IntPtr HWND_NOTOPMOST = (IntPtr)-2;
        public static IntPtr HWND_TOP = (IntPtr)0;
        // public static IntPtr HWND_TOPMOST = (IntPtr)-1;
        public static uint SWP_NOSIZE = 1;
        public static uint SWP_NOZORDER = 4;
        [DllImport("user32.dll", EntryPoint = "SetWindowPos")]
        public static extern IntPtr SetWindowPos(IntPtr hWnd, int hWndInsertAfter, int x, int Y, int cx, int cy, uint wFlags);
    }
    class Program
    {
        static void Main(string[] args)
        {
            var consoleWnd = System.Diagnostics.Process.GetCurrentProcess().MainWindowHandle;
            Imports.SetWindowPos(consoleWnd, 0, 0, 0, 0, 0, Imports.SWP_NOSIZE | Imports.SWP_NOZORDER);
            System.Console.ReadLine();
        }
    }
}
The code moves the console window to the top left of your screen, not changing z-order nor changing width/height of the window.