C# How to remove custom TabControl border or header

Question

I have been experiencing an issue with my custom TabControl. I cannot remove a Border from the TabControl.

Here is the code of the TabControl.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Drawing;
using System.Windows.Forms;
using System.Text;
using System.Threading.Tasks;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Drawing.Drawing2D;

namespace GoatUserControls
{
    public partial class GoatTab : TabControl
    {
    public static bool N_PositionMode;
    public static bool N_PlusButton;

    public GoatTab()
    {
        DrawMode = TabDrawMode.OwnerDrawFixed;
        SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.OptimizedDoubleBuffer | ControlStyles.ResizeRedraw | ControlStyles.UserPaint | ControlStyles.SupportsTransparentBackColor, true);
        DoubleBuffered = true;
        SizeMode = TabSizeMode.Fixed;
        ItemSize = new System.Drawing.Size(120, 30);
        N_PositionMode = false;
        N_PlusButton = false;
        this.DrawMode = TabDrawMode.OwnerDrawFixed;
        SetWindowTheme(this.Handle, "", "");
        //var tab = new TabPadding(this);
    }

    [DllImportAttribute("uxtheme.dll")]
    private static extern int SetWindowTheme(IntPtr hWnd, string appname, string idlist);

    //All Properties
    [Description("Desides if the Tab Control will display in vertical mode."), Category("Design"), Browsable(true), EditorBrowsable(EditorBrowsableState.Always)]
    public bool VerticalMode{ get { return N_PositionMode; } set { N_PositionMode = value; if (N_PositionMode == true) { SetToVerticalMode(); } if (N_PositionMode == false) { SetToHorrizontalMode(); } }}

    //Method for all of the properties
    private void SetToHorrizontalMode(){ ItemSize = new System.Drawing.Size(120, 30); this.Alignment = TabAlignment.Top; }
    private void SetToVerticalMode(){ ItemSize = new System.Drawing.Size(30, 120); Alignment = TabAlignment.Left; }


    protected override void CreateHandle()
    {
        base.CreateHandle();
        Alignment = TabAlignment.Top;
    }

    protected override void OnPaint(PaintEventArgs e)
    {

        Bitmap B = new Bitmap(Width, Height);

        Graphics G = Graphics.FromImage(B);

        G.Clear(Color.Gainsboro);

        Color NonSelected = Color.FromArgb(62, 62, 62);
        Color Selected = Color.FromArgb(0, 172, 219);

        SolidBrush NOSelect = new SolidBrush(NonSelected);
        SolidBrush ISSelect = new SolidBrush(Selected);

        for (int i = 0; i <= TabCount - 1; i++)
        {
            Rectangle TabRectangle = GetTabRect(i);

            if (i == SelectedIndex)
            {
                //Tab is selected
                G.FillRectangle(ISSelect, TabRectangle);
            }
            else
            {
                //Tab is not selected
                G.FillRectangle(NOSelect, TabRectangle);
            }

            StringFormat sf = new StringFormat();

            sf.LineAlignment = StringAlignment.Center;
            sf.Alignment = StringAlignment.Center;

            Font font = new Font("Segoe UI", 10.0f);

            G.DrawString(TabPages[i].Text, font, Brushes.White, TabRectangle, sf);

            TabPages[i].BackColor = Color.FromArgb(62, 62, 62);
            //TabPages[i].Padding = Point(0, 0);

        }

        e.Graphics.DrawImage(B, 0, 0);
        G.Dispose();
        B.Dispose();
        base.OnPaint(e);

    }

}
}

I think the Border is a background of the control. So most likely the question is how can I remove the background of a control. Do you guys have any ideas?