http://stackoverflow.com/questions/7204156/how-to-hide-checkbox-of-the-certain-treenode-in-treeview-control-using-c4-0-win

treeview hide checkbox.cs

using System.Runtime.InteropServices

public const int TVIF_STATE = 0x8;
public const int TVIS_STATEIMAGEMASK = 0xF000;
public const int TV_FIRST= 0x1100;
public const int  TVM_SETITEM = TV_FIRST + 63;

public struct TVITEM
{
    public int mask;
    public IntPtr hItem;
    public int state;
    public int stateMask;
    [MarshalAs(UnmanagedType.LPTStr)]
    public String lpszText;
    public int cchTextMax;
    public int iImage;
    public int iSelectedImage;
    public int cChildren;
    public IntPtr lParam;
}

[DllImport("user32.dll")]
static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

private void button1_Click(object sender, System.EventArgs e)
{
    this.treeView1.SelectedNode=this.treeView1.Nodes[0];
    TVITEM tvi=new TVITEM();
    tvi.hItem=this.treeView1.SelectedNode.Handle;
    tvi.mask=TVIF_STATE;
    tvi.stateMask = TVIS_STATEIMAGEMASK;
    tvi.state=0;
    IntPtr lparam=Marshal.AllocHGlobal(Marshal.SizeOf(tvi));
    Marshal.StructureToPtr(tvi, lparam, false);
    SendMessage(this.treeView1.Handle, TVM_SETITEM, IntPtr.Zero, lparam);
}